/* Global Reset & Styling Variables */
:root {
  --bg-primary: #0a0e17;
  --bg-secondary: #121824;
  --bg-card: rgba(22, 30, 46, 0.7);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-color-glow: rgba(0, 240, 255, 0.3);
  
  /* HSL Tailored Neon Color Palette */
  --text-main: #e2e8f0;
  --text-muted: #94a3b8;
  --neon-cyan: hsl(180, 100%, 50%);
  --neon-cyan-glow: hsla(180, 100%, 50%, 0.15);
  --neon-blue: hsl(210, 100%, 55%);
  --neon-purple: hsl(270, 90%, 60%);
  --neon-purple-glow: hsla(270, 90%, 60%, 0.2);
  
  --success-color: hsl(142, 70%, 45%);
  --success-glow: hsla(142, 70%, 45%, 0.15);
  --error-color: hsl(350, 80%, 55%);
  --error-glow: hsla(350, 80%, 55%, 0.15);
  
  --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --glass-blur: blur(12px);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Outfit', 'Noto Sans JP', sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-main);
  overflow: hidden; /* Hide outer browser window scrollbars completely */
  height: 100vh;
}

/* Premium Custom Scrollbars */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.1);
  border-radius: 3px;
  transition: var(--transition-smooth);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--neon-cyan);
}

/* App Container Layout */
.app-container {
  display: flex;
  flex-direction: column;
  height: 100vh;
  background-image: 
    radial-gradient(circle at 12% 15%, rgba(0, 242, 254, 0.07) 0%, transparent 45%),
    radial-gradient(circle at 88% 85%, rgba(0, 136, 255, 0.07) 0%, transparent 45%),
    radial-gradient(circle at 50% 50%, rgba(10, 15, 30, 1) 0%, #030712 100%);
  background-attachment: fixed;
}


/* Header styling */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 24px;
  background: rgba(10, 14, 23, 0.8);
  backdrop-filter: var(--glass-blur);
  border-bottom: 1px solid var(--border-color);
  z-index: 100;
}

.header-logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-icon {
  font-size: 28px;
  background: linear-gradient(135deg, var(--neon-cyan), var(--neon-blue));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 8px var(--neon-cyan-glow));
}

.logo-text h1 {
  font-size: 18px;
  font-weight: 700;
  letter-spacing: 0.5px;
}

.logo-text span {
  font-size: 11px;
  color: var(--text-muted);
}

.sidebar-progress {
  padding: 16px 20px 12px 20px;
  border-bottom: 1px solid var(--border-color);
  background: rgba(255, 255, 255, 0.02);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.progress-info {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-muted);
}

.progress-info strong {
  color: var(--neon-cyan);
}

.progress-bar-container {
  height: 6px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 3px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--neon-blue), var(--neon-cyan));
  border-radius: 3px;
  box-shadow: 0 0 8px var(--neon-cyan);
  transition: width 0.5s ease-out;
}

.reset-all-btn {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--text-muted);
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}

.reset-all-btn:hover {
  border-color: var(--error-color);
  color: var(--error-color);
  box-shadow: 0 0 6px var(--error-glow);
}

/* App Body Area */
.app-body {
  display: flex;
  flex: 1;
  overflow: hidden;
}

/* Sidebar Styling */
.app-sidebar {
  width: 280px;
  background: rgba(18, 24, 36, 0.6);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.sidebar-title {
  padding: 16px 20px;
  font-size: 14px;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 8px;
  border-bottom: 1px solid var(--border-color);
  color: var(--neon-cyan);
}

.lessons-nav {
  flex: 1;
  overflow-y: auto;
  padding: 12px;
}

/* Section dividers inside sidebar */
.sidebar-section-header {
  font-size: 11px;
  color: var(--text-muted);
  text-transform: uppercase;
  margin: 16px 8px 8px 8px;
  letter-spacing: 1px;
  font-weight: 700;
}

.lessons-nav::-webkit-scrollbar {
  width: 4px;
}

.lessons-nav::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.1);
  border-radius: 2px;
}

.lesson-nav-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 12px;
  border-radius: 8px;
  cursor: pointer;
  margin-bottom: 4px;
  font-size: 13px;
  color: var(--text-muted);
  transition: var(--transition-smooth);
  border: 1px solid transparent;
}

.lesson-nav-item:hover {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-main);
}

.lesson-nav-item.active {
  background: linear-gradient(90deg, rgba(0, 242, 254, 0.12), rgba(0, 168, 255, 0.02)) !important;
  color: #ffffff !important;
  border-left: 3px solid var(--neon-cyan) !important;
  border-top-left-radius: 0;
  border-bottom-left-radius: 0;
  box-shadow: inset 4px 0 8px rgba(0, 242, 254, 0.1), 0 0 10px rgba(0, 242, 254, 0.12);
  font-weight: 600;
  text-shadow: 0 0 6px rgba(0, 242, 254, 0.35);
}


.lesson-nav-item .nav-status-icon {
  font-size: 14px;
}

.lesson-nav-item.completed .nav-status-icon {
  color: var(--success-color);
  filter: drop-shadow(0 0 4px var(--success-glow));
}

.lesson-nav-item.completed {
  background: rgba(16, 185, 129, 0.03);
}

.lesson-nav-item.completed:hover {
  background: rgba(16, 185, 129, 0.06);
}

/* Center: Lesson Content Panel */
.lesson-content {
  flex: 1.1;
  padding: 20px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.content-card {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 24px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.lesson-header {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 16px;
}

.lesson-badge {
  display: inline-block;
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 11px;
  background: var(--neon-purple-glow);
  color: var(--neon-purple);
  border: 1px solid rgba(168, 85, 247, 0.2);
  margin-bottom: 8px;
  font-weight: 600;
  letter-spacing: 0.5px;
}

.lesson-header h2 {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 4px;
}

.lesson-header h3 {
  font-size: 14px;
  font-weight: 400;
  color: var(--text-muted);
}

/* Language selector tabs */
.lang-tabs {
  display: flex;
  background: rgba(0, 0, 0, 0.2);
  padding: 4px;
  border-radius: 8px;
  gap: 4px;
  width: fit-content;
  border: 1px solid var(--border-color);
}

.lang-tab {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition-smooth);
  display: flex;
  align-items: center;
  gap: 6px;
}

.lang-tab:hover {
  color: var(--text-main);
}

.lang-tab.active {
  background: rgba(255, 255, 255, 0.08);
  color: var(--neon-cyan);
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
}

/* Concept Body Layout */
.concept-container {
  display: flex;
  gap: 20px;
  transition: var(--transition-smooth);
}

.concept-col {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.concept-col h4 {
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--neon-cyan);
  display: flex;
  align-items: center;
  gap: 6px;
}

.concept-col.zh-col h4 {
  color: var(--neon-blue);
}

.concept-body {
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-main);
  background: rgba(0, 0, 0, 0.15);
  border: 1px solid var(--border-color);
  padding: 16px;
  border-radius: 10px;
  white-space: pre-line;
}
.concept-body strong {
  color: var(--neon-cyan);
  font-weight: 650;
}
.concept-body code {
  background: rgba(255, 255, 255, 0.08);
  color: #ff9e64; /* orange-yellow tone for code */
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
  font-family: 'Fira Code', monospace;
}
.concept-body .vocab-highlight {
  color: #bb9af7; /* vibrant purple for bilingual vocab highlights */
  font-weight: bold;
}

/* Analogy Card */
.analogy-card {
  display: flex;
  gap: 16px;
  background: rgba(252, 185, 0, 0.04);
  border: 1px solid rgba(252, 185, 0, 0.15);
  border-radius: 10px;
  padding: 16px;
}

.analogy-card .card-icon {
  font-size: 24px;
  color: #fcb900;
  filter: drop-shadow(0 0 6px rgba(252, 185, 0, 0.2));
}

.analogy-card .card-content h5 {
  font-size: 13px;
  color: #fcb900;
  margin-bottom: 4px;
}

.analogy-card .card-content p {
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--text-main);
}

/* Code Example Card */
.example-card {
  background: #060913;
  border: 1px solid var(--border-color);
  border-radius: 10px;
  overflow: hidden;
}

.example-header {
  background: rgba(255, 255, 255, 0.02);
  padding: 8px 16px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 12px;
  color: var(--text-muted);
}

.copy-example-btn {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: var(--neon-cyan);
  padding: 4px 10px;
  border-radius: 4px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: var(--transition-smooth);
}

.copy-example-btn:hover {
  background: rgba(0, 240, 255, 0.08);
  border-color: var(--neon-cyan);
}

.example-card pre {
  padding: 16px;
  overflow-x: auto;
  font-family: 'Fira Code', monospace;
  font-size: 14px;
}

.example-card code {
  color: #38bdf8;
}

/* Quiz Section */
.quiz-section {
  border-top: 1px solid var(--border-color);
  padding-top: 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.quiz-section h4 {
  font-size: 14px;
  color: var(--neon-purple);
  display: flex;
  align-items: center;
  gap: 6px;
}

.quiz-question {
  font-size: 14px;
  line-height: 1.5;
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.02);
  padding: 12px;
  border-radius: 8px;
  border-left: 3px solid var(--neon-purple);
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.quiz-option {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  cursor: pointer;
  font-size: 13.5px;
  transition: var(--transition-smooth);
}

.quiz-option:hover {
  background: rgba(255, 255, 255, 0.02);
  border-color: rgba(255, 255, 255, 0.2);
}

.quiz-option.selected {
  border-color: var(--neon-purple);
  background: var(--neon-purple-glow);
}

.quiz-option .option-marker {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 2px solid var(--text-muted);
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 11px;
  font-weight: 700;
  transition: var(--transition-smooth);
}

.quiz-option.selected .option-marker {
  border-color: var(--neon-purple);
  background: var(--neon-purple);
  color: #fff;
}

.quiz-footer {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-top: 6px;
}

.quiz-submit-btn {
  background: linear-gradient(135deg, #7c3aed, #a855f7);
  border: none;
  color: #fff;
  padding: 10px 20px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition-smooth);
  box-shadow: 0 4px 12px var(--neon-purple-glow);
}

.quiz-submit-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 16px rgba(168, 85, 247, 0.4);
}

.quiz-feedback {
  flex: 1;
  padding: 10px 14px;
  border-radius: 8px;
  font-size: 13px;
  line-height: 1.4;
  animation: slideIn 0.3s ease;
}

.quiz-feedback.success {
  background: var(--success-glow);
  border: 1px solid var(--success-color);
  color: #34d399;
}

.quiz-feedback.error {
  background: var(--error-glow);
  border: 1px solid var(--error-color);
  color: #f87171;
}

.hidden {
  display: none !important;
}

/* Right: Playground Panel Layout */
.playground-section {
  flex: 0.9;
  padding: 20px 20px 20px 0;
  display: flex;
  flex-direction: column;
  gap: 20px;
  overflow: hidden; /* Fixed height, no parent scrollbar */
  height: 100%;
}

.playground-card {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Card specific sizing rules for layout optimization */
.schema-card {
  flex: 0 0 auto;
  transition: var(--transition-smooth);
}

.console-card {
  flex: 1.3;
  min-height: 220px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.console-card-body {
  flex: 1;
  min-height: 0;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

/* Editor area scrolls, footer stays fixed at bottom */
.console-card-body .playground-task-desc {
  flex: 0 0 auto;
}

.console-card-body .editor-container {
  flex: 0 1 auto;
  min-height: 80px;
  max-height: 300px;
  overflow: hidden;
}

/* Keep footer always visible — the key fix for the invisible button */
.console-card-body .console-footer {
  flex: 0 0 auto;
}

.output-card {
  flex: 1;
  min-height: 140px;
}

/* Collapsed state for pro-docking panel height redistribution */
.playground-card.collapsed {
  flex: 0 0 auto !important;
  min-height: 0 !important;
  height: auto !important;
}

/* ====== Header Challenge Widget Styling ====== */
.header-challenge {
  display: flex;
  align-items: center;
  gap: 12px;
  background: transparent;
  border: none;
  padding: 0;
  transition: var(--transition-smooth);
  margin-right: 12px; /* Spacing before reset button */
}

.header-challenge-btn-start {
  background: rgba(249, 115, 22, 0.08);
  border: 1px solid rgba(249, 115, 22, 0.25);
  color: #fb923c;
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
  height: 30px;
}

.header-challenge-btn-start:hover {
  background: rgba(249, 115, 22, 0.18);
  border-color: #fb923c;
  box-shadow: 0 0 10px rgba(249, 115, 22, 0.25);
}

.challenge-active-controls {
  display: flex;
  align-items: center;
  gap: 10px;
}

.challenge-status-text {
  font-size: 12px;
  font-weight: 600;
  color: #fb923c;
  text-shadow: 0 0 6px rgba(249, 115, 22, 0.2);
}

.challenge-source-tag {
  font-size: 10px;
  font-weight: 600;
  color: var(--neon-purple);
  background: var(--neon-purple-glow);
  border: 1px solid rgba(168, 85, 247, 0.3);
  padding: 2px 6px;
  border-radius: 4px;
  white-space: nowrap;
}

.challenge-control-btn {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: var(--text-muted);
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 11px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: var(--transition-smooth);
  height: 26px;
}

.challenge-control-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.3);
  color: var(--text-main);
}

.challenge-control-btn.stop-btn {
  background: rgba(239, 68, 68, 0.1);
  border-color: rgba(239, 68, 68, 0.25);
  color: #f87171;
}

.challenge-control-btn.stop-btn:hover {
  background: rgba(239, 68, 68, 0.2);
  border-color: #ef4444;
  color: #fff;
}

/* DB Group Switcher Tabs */
.db-group-tabs {
  display: flex;
  background: rgba(0,0,0,0.2);
  border-radius: 6px;
  padding: 3px;
  gap: 3px;
  border: 1px solid var(--border-color);
}

.db-group-tab {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 4px 10px;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: var(--transition-smooth);
  white-space: nowrap;
}

.db-group-tab:hover {
  color: var(--text-main);
}

.db-group-tab.active {
  background: rgba(255,255,255,0.08);
  color: var(--neon-cyan);
}



.schema-header {
  padding: 14px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  font-weight: 600;
  color: var(--neon-cyan);
  border-bottom: 1px solid var(--border-color);
  cursor: pointer;
  background: rgba(0, 0, 0, 0.1);
}

.schema-header:hover {
  background: rgba(255, 255, 255, 0.02);
}

.toggle-icon {
  font-size: 12px;
  transition: var(--transition-smooth);
  color: var(--text-muted);
  cursor: pointer;
}

.toggle-icon:hover {
  color: var(--text-main);
}

.collapsed .toggle-icon {
  transform: rotate(-90deg);
}

.schema-body {
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.schema-tabs {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.schema-tab {
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 5px 10px;
  border-radius: 6px;
  font-size: 12px;
  cursor: pointer;
  transition: var(--transition-smooth);
}

.schema-tab:hover {
  color: var(--text-main);
  border-color: rgba(255, 255, 255, 0.15);
}

.schema-tab.active {
  border-color: var(--neon-cyan);
  color: var(--neon-cyan);
  background: var(--neon-cyan-glow);
}

.schema-table-details {
  background: rgba(0, 0, 0, 0.15);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 10px;
  max-height: 200px;
  overflow-y: auto;
}

.schema-table-details h6 {
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 6px;
  text-transform: uppercase;
}

.schema-col-list {
  list-style: none;
  font-size: 12px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.schema-col-list li {
  display: flex;
  justify-content: space-between;
  border-bottom: 1px solid rgba(255,255,255,0.03);
  padding-bottom: 4px;
}

.schema-col-name {
  font-family: 'Fira Code', monospace;
  color: #38bdf8;
}

.schema-col-name.primary-key {
  color: #fbbf24;
}

.schema-col-type {
  color: #818cf8;
}

.schema-col-desc {
  color: var(--text-muted);
  margin-left: 8px;
}

/* Console details */
.console-header {
  padding: 14px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-main);
  border-bottom: 1px solid var(--border-color);
}

.console-actions {
  display: flex;
  gap: 8px;
}

/* Random practice button default state */
.random-practice-btn {
  background: rgba(0, 240, 255, 0.05) !important;
  border-color: rgba(0, 240, 255, 0.2) !important;
  color: var(--neon-cyan) !important;
  font-weight: 500;
}

.random-practice-btn.active-practice {
  background: rgba(168, 85, 247, 0.1) !important;
  border-color: rgba(168, 85, 247, 0.3) !important;
  color: var(--neon-purple) !important;
}

/* Change-question button */
.change-practice-btn-style {
  background: rgba(252, 185, 0, 0.05) !important;
  border-color: rgba(252, 185, 0, 0.2) !important;
  color: #fcb900 !important;
  font-weight: 500;
}

.console-btn {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: var(--text-muted);
  padding: 4px 8px;
  border-radius: 5px;
  font-size: 11px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: var(--transition-smooth);
}

.console-btn:hover {
  color: var(--text-main);
  border-color: rgba(255, 255, 255, 0.25);
}

.playground-task-desc {
  padding: 12px 20px;
  background: rgba(0, 240, 255, 0.03);
  border-bottom: 1px solid var(--border-color);
  font-size: 12.5px;
  line-height: 1.5;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.task-desc-main {
  display: flex;
  flex-direction: column;
  gap: 2px;
  flex: 1;
}

.task-desc-actions {
  display: flex;
  gap: 6px;
  flex-shrink: 0;
}

.playground-task-desc i {
  color: var(--neon-cyan);
}

.editor-container {
  display: flex;
  flex: 1;
  min-height: 180px;
  background: #040711;
}

.line-numbers {
  width: 36px;
  padding: 12px 0;
  text-align: center;
  background: rgba(0,0,0,0.3);
  color: rgba(255,255,255,0.15);
  font-family: 'Fira Code', monospace;
  font-size: 14px;
  line-height: 1.6;
  border-right: 1px solid var(--border-color);
  user-select: none;
}

.sql-editor {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  padding: 12px;
  color: #a5f3fc;
  font-family: 'Fira Code', monospace;
  font-size: 14px;
  line-height: 1.6;
  resize: none; /* Disable manual resize to maintain alignment */
}

.console-footer {
  padding: 10px 20px;
  background: rgba(0,0,0,0.15);
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.run-area {
  display: flex;
  align-items: center;
  gap: 10px;
}

.shortcut-hint {
  font-size: 10.5px;
  color: rgba(255,255,255,0.2);
  display: flex;
  align-items: center;
  gap: 4px;
}

.shortcut-hint kbd {
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 3px;
  padding: 1px 4px;
  font-family: 'Fira Code', monospace;
  font-size: 10px;
}

.playground-status {
  font-size: 12px;
}

.status-ready {
  color: var(--text-muted);
}

.status-success {
  color: var(--success-color);
  font-weight: 500;
}

.status-error {
  color: var(--error-color);
  font-weight: 500;
}

.run-query-btn {
  background: linear-gradient(135deg, #0077ff, #00f0ff);
  border: none;
  color: #000;
  padding: 8px 18px;
  border-radius: 6px;
  font-size: 12.5px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
  animation: pulse-glow 3s infinite ease-in-out;
}

.run-query-btn kbd {
  font-size: 10px;
  background: rgba(0, 0, 0, 0.08);
  color: #09090b;
  padding: 1px 5px;
  border-radius: 3px;
  border: 1px solid rgba(0, 0, 0, 0.15);
  margin-left: 6px;
  font-family: 'Fira Code', monospace;
  font-weight: 500;
}

.run-query-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 0 20px rgba(0, 242, 254, 0.8), 0 0 30px rgba(0, 136, 255, 0.4);
}

/* Output Card styling */
.output-card {
  flex: 1;
  min-height: 160px;
}

.output-header {
  padding: 10px 20px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 12.5px;
  color: var(--text-muted);
  background: rgba(0, 0, 0, 0.1);
}

.output-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Maximize button in output header */
.maximize-btn {
  background: transparent !important;
  border: 1px solid rgba(255,255,255,0.1) !important;
  color: var(--text-muted) !important;
  padding: 4px 8px !important;
  font-size: 11px !important;
  display: flex !important;
  align-items: center !important;
  gap: 4px !important;
  transition: var(--transition-smooth) !important;
}

.maximize-btn.active {
  color: var(--neon-cyan) !important;
  border-color: var(--neon-cyan) !important;
}

.row-count-badge {
  background: rgba(255,255,255,0.06);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 11px;
}

.output-body {
  padding: 12px;
  overflow: auto;
  flex: 1;
  background: rgba(0,0,0,0.2);
}

.output-placeholder {
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  color: rgba(255, 255, 255, 0.12);
  gap: 8px;
  padding: 24px 0;
}

.output-placeholder i {
  font-size: 32px;
}

.output-placeholder p {
  font-size: 13px;
  font-weight: 500;
}

.output-placeholder span {
  font-size: 11px;
}

/* Output error card style */
.output-error-box {
  background: rgba(239, 68, 68, 0.05);
  border: 1px dashed var(--error-color);
  color: #fca5a5;
  padding: 16px;
  border-radius: 8px;
  font-family: 'Fira Code', monospace;
  font-size: 13px;
  line-height: 1.5;
  white-space: pre-wrap;
}

.output-message-box {
  background: rgba(16, 185, 129, 0.05);
  border: 1px dashed var(--success-color);
  color: #6ee7b7;
  padding: 12px;
  border-radius: 8px;
  font-size: 13px;
  margin-bottom: 12px;
}

/* Grid Table Formatting */
.result-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 12.5px;
  text-align: left;
}

.result-table th {
  background: rgba(255, 255, 255, 0.04);
  color: var(--neon-cyan);
  padding: 8px 12px;
  font-weight: 600;
  border-bottom: 2px solid var(--border-color);
  font-family: 'Fira Code', monospace;
}

.result-table td {
  padding: 8px 12px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.04);
  font-family: 'Fira Code', monospace;
}

.result-table tr:hover {
  background: rgba(255, 255, 255, 0.02);
}

.result-table tr:nth-child(even) {
  background: rgba(255, 255, 255, 0.01);
}

/* Maximized Output Card Styles */
.maximize-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(4px);
  z-index: 9998;
  animation: fadeIn 0.2s ease;
}

.maximize-overlay.visible {
  display: block;
}

.output-card.maximized {
  position: fixed;
  top: 5vh;
  left: 50%;
  transform: translateX(-50%);
  width: min(92vw, 1100px);
  height: 88vh;
  z-index: 9999;
  background: #0b0f19;
  backdrop-filter: var(--glass-blur);
  border: 1.5px solid var(--neon-cyan);
  box-shadow: 0 0 60px rgba(0, 240, 255, 0.3), 0 24px 80px rgba(0,0,0,0.8);
  border-radius: 16px;
  animation: scaleIn 0.25s cubic-bezier(0.34, 1.56, 0.64, 1) forwards;
}

.output-card.maximized .output-body {
  padding: 20px;
  max-height: calc(88vh - 52px);
  overflow: auto;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

@keyframes scaleIn {
  from {
    opacity: 0;
    transform: translateX(-50%) scale(0.94);
  }
  to {
    opacity: 1;
    transform: translateX(-50%) scale(1);
  }
}

/* Slide-in animation (used by quiz feedback) */
@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Toast Notification */
.sql-toast {
  position: fixed;
  bottom: 28px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: rgba(18, 24, 40, 0.95);
  backdrop-filter: blur(16px);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 10px;
  padding: 12px 20px;
  font-size: 13px;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 10px;
  z-index: 99999;
  box-shadow: 0 8px 32px rgba(0,0,0,0.5);
  max-width: 520px;
  opacity: 0;
  transition: opacity 0.3s ease, transform 0.3s cubic-bezier(0.34, 1.56, 0.64, 1);
  pointer-events: none;
}

.sql-toast.visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

.sql-toast-info {
  border-color: rgba(0, 240, 255, 0.25);
}

.sql-toast-info i {
  color: var(--neon-cyan);
}

.sql-toast-success {
  border-color: rgba(52, 211, 153, 0.3);
}

.sql-toast-success i {
  color: var(--success-color);
}

.sql-toast-error {
  border-color: rgba(239, 68, 68, 0.3);
}

.sql-toast-error i {
  color: var(--error-color);
}

/* Responsiveness */

/* Mobile sidebar toggle & backdrop — hidden on desktop */
.mobile-sidebar-toggle,
.mobile-sidebar-backdrop {
  display: none;
}

/* ================================================================
   断点 1: 1024px – 1200px — 缩窄 sidebar、保证顶部 header 不挤
   ================================================================ */
@media (max-width: 1200px) and (min-width: 769px) {
  .app-sidebar {
    width: 220px;
  }
  .header-logo {
    flex: 0 0 180px;
    min-width: 160px;
  }
  .logo-text h1 {
    font-size: 15px;
    max-width: 140px;
  }
  .logo-text span {
    display: none;
  }
  .subject-tab {
    padding: 5px 10px !important;
    font-size: 11.5px !important;
  }
  .header-challenge-btn-start {
    padding: 4px 8px;
    font-size: 11px;
  }
  .challenge-control-btn {
    padding: 2px 6px;
    font-size: 10px;
  }
  .console-card-body .editor-container {
    max-height: 240px;
  }
}

/* ================================================================
   断点 2: 768px 以下 — 三栏改单栏、sidebar 变左侧抽屉
   ================================================================ */
@media (max-width: 768px) {
  .app-body {
    flex-direction: column;
    overflow-y: auto;
  }

  /* Mobile sidebar toggle button */
  .mobile-sidebar-toggle {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 14px;
    background: rgba(0, 240, 255, 0.08);
    border: 1px solid rgba(0, 240, 255, 0.2);
    color: var(--neon-cyan);
    border-radius: 6px;
    font-size: 12px;
    font-weight: 600;
    cursor: pointer;
    margin: 8px 14px 0;
    z-index: 10;
    transition: var(--transition-smooth);
  }

  .mobile-sidebar-toggle:hover {
    background: rgba(0, 240, 255, 0.18);
    border-color: var(--neon-cyan);
  }

  /* Sidebar becomes a fixed-position drawer, hidden off-screen by default */
  .app-sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: 280px;
    height: 100vh;
    z-index: 200;
    transform: translateX(-100%);
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border-right: 1px solid var(--border-color);
    flex-shrink: 0;
    overflow-y: auto;
  }

  /* Drawer open state */
  body.mobile-sidebar-open .app-sidebar {
    transform: translateX(0);
  }

  /* Backdrop overlay */
  .mobile-sidebar-backdrop {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 150;
  }

  body.mobile-sidebar-open .mobile-sidebar-backdrop {
    display: block;
  }

  .lesson-content {
    flex: 0 0 auto;
    min-height: auto;
    max-height: none;
    overflow-y: visible;
    padding: 14px;
    gap: 14px;
  }

  /* 右栏 playground 取消 overflow:hidden，改为可滚动区域 */
  .playground-section {
    overflow-y: visible;
    overflow-x: hidden;
    height: auto;
    min-height: 0;
    padding: 14px;
    gap: 14px;
    flex: 0 0 auto;
  }

  .playground-card {
    min-height: 0;
    flex: 0 0 auto;
  }

  .console-card {
    flex: 0 0 auto;
    min-height: 220px;
  }

  .output-card {
    flex: 0 0 auto;
    min-height: 140px;
  }

  /* 中日双栏改为上下排列 */
  .concept-container {
    flex-direction: column;
    gap: 14px;
  }

  .concept-col {
    flex: 0 0 auto;
  }

  /* SQL editor 缩小 */
  .console-card-body .editor-container {
    max-height: 200px;
  }

  .sql-editor {
    font-size: 13px !important;
    padding: 10px !important;
  }

  .run-query-btn {
    padding: 8px 14px !important;
    font-size: 12px !important;
  }
}

/* ================================================================
   断点 3: 480px 以下 — 手机尺寸，全面压缩间距
   ================================================================ */
@media (max-width: 480px) {
  .app-header {
    padding: 8px 10px;
    gap: 6px;
    flex-wrap: wrap;
    min-height: auto;
  }

  .header-logo {
    flex: 0 0 auto;
    min-width: 0;
    gap: 6px;
  }

  .logo-icon {
    font-size: 20px;
  }

  .logo-text h1 {
    font-size: 14px;
  }

  .logo-text span {
    display: none;
  }

  .header-subject-selector {
    margin-left: 0;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    flex: 1 1 100%;
    order: 3;
  }

  .subject-tab {
    padding: 6px 10px !important;
    font-size: 11px !important;
    white-space: nowrap !important;
  }

  .header-challenge {
    order: 4;
    margin-right: 0;
  }

  .header-challenge-btn-start {
    padding: 6px 10px;
    font-size: 11px;
  }

  .theme-toggle-btn,
  .reset-all-btn {
    padding: 4px 8px;
    font-size: 10px;
  }

  .sub-header-tab {
    padding: 6px 10px !important;
    font-size: 11px !important;
  }

  /* App body: compact mobile toggle and drawer */
  .mobile-sidebar-toggle {
    margin: 6px 10px 0;
    padding: 7px 10px;
    font-size: 11px;
  }

  .app-sidebar {
    width: 260px;
  }

  .lesson-content {
    padding: 10px;
    gap: 10px;
  }

  .content-card {
    padding: 14px;
    gap: 12px;
    border-radius: 12px;
  }

  .lesson-header h2 {
    font-size: 16px;
  }

  .lesson-header h3 {
    font-size: 12px;
  }

  .playground-section {
    padding: 10px;
    gap: 10px;
  }

  .console-header,
  .schema-header,
  .output-header {
    padding: 8px 14px;
  }

  .console-card-body .editor-container {
    max-height: 160px;
    min-height: 60px;
  }

  .sql-editor {
    font-size: 12px !important;
    line-height: 1.5;
    padding: 8px !important;
  }

  .console-footer {
    padding: 8px 14px;
  }

  /* SQL 执行按钮 — 触控高度至少 40px */
  .run-query-btn {
    padding: 10px 16px !important;
    font-size: 13px !important;
    min-height: 40px !important;
  }

  .run-query-btn kbd {
    display: none;
  }

  /* 结果表格横向滚动 */
  .result-table {
    font-size: 11px !important;
  }

  .result-table th,
  .result-table td {
    padding: 6px 8px !important;
  }

  .output-body {
    overflow-x: auto;
  }

  .playground-task-desc {
    font-size: 11px !important;
    padding: 6px 14px;
  }

  /* Quiz 按钮触控优化 */
  .quiz-submit-btn {
    min-height: 40px;
    padding: 10px 16px;
  }

  .quiz-option {
    padding: 10px 12px;
  }

  /* Schema card */
  .schema-card {
    min-height: 0;
  }

  /* sub-header-bar: reduce padding, allow horizontal scroll to prevent document overflow */
  .sub-header-bar {
    padding: 8px 10px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .sub-header-tabs {
    flex-shrink: 0;
    gap: 8px;
  }

  .sub-header-tab {
    padding: 6px 10px !important;
    font-size: 11.5px !important;
    white-space: nowrap;
  }
}

/* ================================================================
   已有补充断点 — 1500px, 1180px, 1200px fallback
   （予以精简，避免和上面的断点冲突）
   ================================================================ */

/* The old max-width:1200px rule (column collapse) is now at 768px.
   Keep this cleanup-compatible by narrowing its scope to height-only fixes. */

/* Height-based optimizations to reduce scrolling on smaller screens */
@media (max-height: 850px) {
  .app-header {
    padding: 8px 16px;
  }
  .logo-icon {
    font-size: 22px;
  }
  .logo-text h1 {
    font-size: 16px;
  }
  .header-challenge {
    gap: 8px;
  }
  .header-challenge-btn-start {
    height: 26px;
    padding: 4px 10px;
    font-size: 11px;
  }
  .challenge-control-btn {
    height: 22px;
    padding: 2px 6px;
    font-size: 10px;
  }
  .reset-all-btn {
    padding: 4px 10px;
    font-size: 11px;
  }
  .lesson-content {
    padding: 12px;
    gap: 12px;
  }
  .content-card {
    padding: 16px;
    gap: 12px;
    border-radius: 12px;
  }
  .lesson-header {
    padding-bottom: 10px;
  }
  .lesson-header h2 {
    font-size: 18px;
  }
  .lesson-header h3 {
    font-size: 12.5px;
  }
  .lang-tabs {
    padding: 2px;
    border-radius: 6px;
  }
  .lang-tab {
    padding: 4px 8px;
    font-size: 11px;
  }
  .concept-col h4 {
    font-size: 12px;
  }
  .concept-body {
    padding: 12px;
    font-size: 13px;
  }
  .analogy-card {
    padding: 10px 14px;
    gap: 12px;
  }
  .analogy-card .card-icon {
    font-size: 20px;
  }
  .analogy-card .card-content p {
    font-size: 12.5px;
  }
  .example-header {
    padding: 6px 12px;
  }
  .example-card pre {
    padding: 12px;
    font-size: 13px;
  }
  .quiz-section {
    padding-top: 12px;
    gap: 10px;
  }
  .quiz-question {
    padding: 10px;
    font-size: 13px;
  }
  .quiz-option {
    padding: 8px 12px;
    font-size: 12.5px;
  }
  .quiz-submit-btn {
    padding: 8px 16px;
    font-size: 12px;
  }
  .playground-section {
    padding: 12px 12px 12px 0;
    gap: 12px;
  }
  .console-header, .schema-header {
    padding: 10px 16px;
  }
  .playground-task-desc {
    padding: 8px 16px;
    font-size: 11.5px;
  }
  .editor-container {
    min-height: 140px;
  }
  .sql-editor {
    font-size: 13px;
    padding: 10px;
  }
  .console-footer, .output-header {
    padding: 8px 16px;
  }
  .output-card {
    min-height: 110px;
  }
  .output-body {
    padding: 10px;
  }
}

/* ==================== MULTI-SUBJECT PORTAL & IT PASSPORT STYLES ==================== */

/* Subject Selector in Header */
.header-subject-selector {
  display: flex;
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 8px;
  padding: 3px;
  gap: 3px;
  margin-left: 20px;
  margin-right: auto;
}

.subject-tab {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}

.subject-tab:hover {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.03);
}

.subject-tab.active {
  background: linear-gradient(135deg, rgba(6, 182, 212, 0.15), rgba(59, 130, 246, 0.15));
  border: 1px solid rgba(6, 182, 212, 0.3);
  color: var(--neon-cyan);
  box-shadow: 0 0 10px rgba(6, 182, 212, 0.2);
}

#subject-tab-itpass.active {
  background: linear-gradient(135deg, rgba(168, 85, 247, 0.15), rgba(236, 72, 153, 0.15));
  border: 1px solid rgba(168, 85, 247, 0.3);
  color: #c084fc;
  box-shadow: 0 0 10px rgba(168, 85, 247, 0.2);
}

/* Sub-Header bar for IT Passport options */
.sub-header-bar {
  display: flex;
  background: #0b0f19;
  border-bottom: 1px solid var(--border-color);
  padding: 8px 24px;
  z-index: 10;
  animation: fadeIn 0.3s ease;
}

.sub-header-tabs {
  display: flex;
  gap: 12px;
}

.sub-header-tab {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  padding: 6px 16px;
  border-radius: 6px;
  font-size: 12.5px;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: var(--transition-smooth);
}

.sub-header-tab:hover {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.02);
}

.sub-header-tab.active {
  background: rgba(168, 85, 247, 0.08);
  border-color: rgba(168, 85, 247, 0.25);
  color: #c084fc;
}

/* IT Passport Widgets */
.itpass-widget .schema-header,
.itpass-widget .console-header,
.itpass-widget .output-header {
  color: #c084fc;
}

/* Vocabulary Flip Flashcards */
.flashcard-desc-box {
  padding: 6px 16px 0;
  font-size: 11px;
  color: var(--text-muted);
  line-height: 1.3;
}

.flashcard-outer {
  perspective: 1000px;
  padding: 6px 16px;
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}

.flashcard {
  width: 100%;
  height: 98px;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
}

.flashcard.flipped {
  transform: rotateY(180deg);
}

.flashcard-front, .flashcard-back {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  border-radius: 12px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 10px 12px;
  text-align: center;
  box-shadow: 0 4px 15px rgba(0,0,0,0.3);
}

.flashcard-front {
  background: linear-gradient(135deg, rgba(88, 28, 135, 0.15), rgba(124, 58, 237, 0.15));
  border: 1.5px solid rgba(168, 85, 247, 0.35);
  color: #e9d5ff;
}

.flashcard-front h3 {
  font-size: 14.5px;
  margin-bottom: 4px;
  color: #f3e8ff;
  font-weight: 600;
}

.flashcard-front span {
  font-size: 10.5px;
  color: #c084fc;
  display: flex;
  align-items: center;
  gap: 4px;
}

.flashcard-back {
  background: linear-gradient(135deg, rgba(124, 58, 237, 0.2), rgba(76, 29, 149, 0.2));
  border: 1.5px solid rgba(168, 85, 247, 0.5);
  color: #fff;
  transform: rotateY(180deg);
}

.flashcard-back h4 {
  font-size: 13.5px;
  color: #a78bfa;
  margin-bottom: 4px;
  font-weight: 600;
}

.flashcard-back p {
  font-size: 11px;
  color: var(--text-muted);
  line-height: 1.35;
  margin-bottom: 4px;
}

.flashcard-back span {
  font-size: 9.5px;
  color: rgba(168, 85, 247, 0.7);
}

.flashcard-footer {
  padding: 10px 16px;
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.flashcard-counter {
  font-size: 11px;
  color: var(--text-muted);
  font-weight: 500;
}

/* Checklist Items */
.checklist-item {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 8px;
  border-bottom: 1px solid rgba(255,255,255,0.03);
  font-size: 12px;
  line-height: 1.4;
}

.checklist-item i {
  color: #c084fc;
  margin-top: 2px;
}

/* Calculators and inputs */
.tool-selector-group {
  margin-bottom: 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.tool-selector-group label {
  font-size: 11px;
  color: var(--text-muted);
}

.tool-selector-group select {
  background: #090d16;
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 6px;
  border-radius: 6px;
  font-size: 12px;
  outline: none;
}

.tool-inputs-container {
  display: flex;
  flex-direction: column;
  gap: 12px;
  font-size: 11.5px;
}

.tool-row {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.tool-row label {
  color: var(--text-muted);
}

.tool-row input {
  background: rgba(0,0,0,0.3);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 6px 10px;
  border-radius: 6px;
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  outline: none;
}

.tool-result {
  background: rgba(168, 85, 247, 0.05);
  border: 1px dashed rgba(168, 85, 247, 0.3);
  padding: 10px;
  border-radius: 6px;
  color: #e9d5ff;
  line-height: 1.5;
}

.tool-result strong {
  color: #f3e8ff;
}

/* CBT Exam Main styles */
.cbt-exam-container {
  display: flex;
  flex: 1;
  background: #070a13;
  width: 100%;
  height: 100%;
  overflow: hidden;
  animation: fadeIn 0.35s ease;
}

/* CBT Configuration view */
.cbt-config-screen {
  display: flex;
  flex: 1;
  justify-content: center;
  align-items: center;
  padding: 40px;
  overflow-y: auto;
}

.cbt-config-card {
  width: 100%;
  max-width: 600px;
  background: rgba(15, 23, 42, 0.4);
  border: 1.5px solid rgba(168, 85, 247, 0.2);
  border-radius: 16px;
  padding: 28px;
  box-shadow: 0 8px 32px rgba(0,0,0,0.5);
  backdrop-filter: var(--glass-blur);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.cbt-config-header-main {
  text-align: center;
}

.cbt-logo-icon {
  font-size: 36px;
  color: #c084fc;
  margin-bottom: 8px;
  filter: drop-shadow(0 0 8px rgba(168,85,247,0.3));
}

.cbt-config-header-main h2 {
  font-size: 20px;
  color: var(--text-main);
  margin-bottom: 6px;
  font-weight: 700;
}

.cbt-config-header-main p {
  font-size: 12.5px;
  color: var(--text-muted);
  line-height: 1.5;
}

.cbt-config-options {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.cbt-option-row {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.cbt-option-row label {
  font-size: 12.5px;
  font-weight: 500;
  color: #e9d5ff;
  display: flex;
  align-items: center;
  gap: 6px;
}

.cbt-option-row select {
  background: #090d16;
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 8px;
  border-radius: 8px;
  font-size: 13px;
  outline: none;
}

.cbt-option-row select:focus {
  border-color: rgba(168, 85, 247, 0.5);
  box-shadow: 0 0 8px rgba(168,85,247,0.25);
}

.cbt-checkbox-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: rgba(0,0,0,0.2);
  padding: 10px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

.cbt-checkbox {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  color: var(--text-muted);
  cursor: pointer;
}

.cbt-checkbox input {
  cursor: pointer;
  accent-color: #c084fc;
}

.cbt-launch-btn {
  background: linear-gradient(135deg, #7c3aed, #db2777);
  border: none;
  color: #fff;
  padding: 12px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: var(--transition-smooth);
}

.cbt-launch-btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 0 16px rgba(168, 85, 247, 0.35);
}

/* CBT Testing Interface */
.cbt-testing-screen {
  display: flex;
  flex-direction: column;
  flex: 1;
  overflow: hidden;
  height: 100%;
}

.cbt-testing-header {
  height: 52px;
  background: #090d16;
  border-bottom: 1px solid var(--border-color);
  padding: 0 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-shrink: 0;
}

.cbt-exam-title-box {
  display: flex;
  align-items: center;
  gap: 10px;
}

.cbt-indicator-badge {
  background: rgba(168, 85, 247, 0.12);
  border: 1px solid rgba(168, 85, 247, 0.25);
  color: #c084fc;
  font-size: 9px;
  font-weight: 700;
  padding: 1px 5px;
  border-radius: 4px;
  display: flex;
  align-items: center;
  gap: 4px;
}

.cbt-exam-display-title {
  font-size: 13.5px;
  font-weight: 600;
  color: var(--text-main);
}

.cbt-exam-timer-box {
  font-size: 13px;
  color: #fca5a5;
  display: flex;
  align-items: center;
  gap: 6px;
  font-weight: 600;
}

.cbt-exam-timer-box strong {
  font-family: 'Fira Code', monospace;
  font-size: 15px;
}

.cbt-exam-actions {
  display: flex;
  gap: 8px;
}

.cbt-btn-action {
  padding: 5px 12px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}

.cbt-btn-action.reset {
  background: rgba(239, 68, 68, 0.08);
  border: 1px solid rgba(239, 68, 68, 0.25);
  color: #f87171;
}

.cbt-btn-action.reset:hover {
  background: rgba(239, 68, 68, 0.2);
  color: #fff;
  border-color: #ef4444;
}

.cbt-btn-action.submit {
  background: linear-gradient(135deg, #7c3aed, #a78bfa);
  border: none;
  color: #fff;
  box-shadow: 0 0 10px rgba(124, 58, 237, 0.2);
}

.cbt-btn-action.submit:hover {
  box-shadow: 0 0 15px rgba(124, 58, 237, 0.4);
  transform: translateY(-0.5px);
}

.cbt-testing-body {
  display: flex;
  flex: 1;
  overflow: hidden;
  height: calc(100% - 52px);
}

.cbt-question-canvas {
  flex: 1;
  overflow-y: auto;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  background: #05070c;
}

.cbt-q-card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 10px;
}

.cbt-q-number {
  font-size: 15px;
  font-weight: 700;
  color: #c084fc;
}

.cbt-q-field {
  font-size: 12px;
  color: var(--text-muted);
}

.cbt-q-flag-btn {
  background: rgba(245, 158, 11, 0.04);
  border: 1px solid rgba(245, 158, 11, 0.2);
  color: #fbbf24;
  padding: 4px 8px;
  border-radius: 5px;
  font-size: 11px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: var(--transition-smooth);
}

.cbt-q-flag-btn.flagged {
  background: #f59e0b !important;
  color: #000 !important;
  border-color: #f59e0b !important;
  font-weight: 600;
}

.cbt-q-body-text {
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-main);
  white-space: pre-wrap;
}

.cbt-q-body-text img {
  max-width: 90%;
  max-height: 240px;
  display: block;
  margin: 10px 0;
  border-radius: 6px;
  background: rgba(255,255,255,0.03);
  border: 1px solid var(--border-color);
  padding: 8px;
}

.cbt-q-body-text table {
  margin: 10px 0;
  border-collapse: collapse;
}

.cbt-q-body-text th, .cbt-q-body-text td {
  border: 1px solid var(--border-color);
  padding: 5px 10px;
  font-size: 12px;
}

.cbt-q-options-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.cbt-option-item {
  width: 100%;
  background: rgba(255, 255, 255, 0.015);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 12px 18px;
  display: flex;
  align-items: flex-start;
  gap: 10px;
  cursor: pointer;
  text-align: left;
  transition: var(--transition-smooth);
  color: var(--text-main);
}

.cbt-option-item:hover {
  background: rgba(255, 255, 255, 0.03);
  border-color: rgba(255, 255, 255, 0.15);
}

.cbt-option-item.selected {
  background: rgba(168, 85, 247, 0.08);
  border-color: #a78bfa;
  box-shadow: 0 0 8px rgba(168, 85, 247, 0.12);
}

.cbt-option-badge {
  background: rgba(0, 0, 0, 0.3);
  color: var(--text-muted);
  border: 1px solid var(--border-color);
  width: 22px;
  height: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-size: 11.5px;
  font-weight: 700;
  flex-shrink: 0;
}

.cbt-option-item.selected .cbt-option-badge {
  background: #a78bfa;
  color: #000;
  border-color: #a78bfa;
}

.cbt-option-text {
  font-size: 13px;
  line-height: 1.4;
  padding-top: 2px;
}

.cbt-q-navigation-bar {
  margin-top: 20px;
  border-top: 1px solid var(--border-color);
  padding-top: 12px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.cbt-nav-btn {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
  color: var(--text-main);
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 12.5px;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}

.cbt-nav-btn:hover {
  background: rgba(255, 255, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.15);
}

.cbt-nav-status {
  font-size: 12px;
  color: var(--text-muted);
}

/* CBT Sidebar Navigator */
.cbt-navigator-panel {
  width: 250px;
  background: #090d16;
  border-left: 1px solid var(--border-color);
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  flex-shrink: 0;
}

.cbt-navigator-panel h5 {
  font-size: 12.5px;
  font-weight: 600;
  color: #e9d5ff;
}

.cbt-grid-canvas {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  align-content: start;
  gap: 5px;
  overflow-y: auto;
  flex: 1;
  padding-right: 2px;
}

.cbt-grid-btn {
  background: rgba(255, 255, 255, 0.01);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  aspect-ratio: 1;
  border-radius: 6px;
  font-size: 11px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  transition: var(--transition-smooth);
}

.cbt-grid-btn:hover {
  background: rgba(255,255,255,0.05);
  color: var(--text-main);
}

.cbt-grid-btn.active {
  border-color: #c084fc !important;
  color: #c084fc !important;
  background: rgba(168, 85, 247, 0.08) !important;
}

.cbt-grid-btn.answered {
  background: rgba(6, 182, 212, 0.12);
  border-color: rgba(6, 182, 212, 0.35);
  color: var(--neon-cyan);
}

.cbt-grid-btn.flagged::after {
  content: "\f024";
  font-family: "Font Awesome 6 Free";
  font-weight: 900;
  position: absolute;
  top: 1px;
  right: 2px;
  font-size: 7px;
  color: #fbbf24;
}

.cbt-grid-legend {
  padding-top: 10px;
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  font-size: 11px;
}

.legend-unit {
  display: flex;
  align-items: center;
  gap: 4px;
  color: var(--text-muted);
}

.legend-color-box {
  width: 10px;
  height: 10px;
  border-radius: 2px;
  display: inline-block;
}

.legend-color-box.cbt-unanswered {
  background: rgba(255,255,255,0.01);
  border: 1px solid var(--border-color);
}

.legend-color-box.cbt-answered {
  background: rgba(6, 182, 212, 0.15);
  border: 1px solid var(--neon-cyan);
}

.legend-color-box.cbt-flagged {
  background: rgba(245, 158, 11, 0.08);
  border: 1px solid #fbbf24;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fbbf24;
  font-size: 6px;
}

/* CBT Results Sheet */
.cbt-results-screen {
  flex: 1;
  overflow-y: auto;
  padding: 30px;
  background: #05070c;
  display: flex;
  justify-content: center;
}

.cbt-results-card {
  width: 100%;
  max-width: 820px;
  background: rgba(15, 23, 42, 0.4);
  border: 1.5px solid rgba(168, 85, 247, 0.2);
  border-radius: 16px;
  padding: 24px;
  backdrop-filter: var(--glass-blur);
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.cbt-results-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 12px;
}

.cbt-results-header h2 {
  font-size: 18px;
  color: var(--text-main);
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 8px;
}

.cbt-results-close-btn {
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  color: var(--text-main);
  padding: 5px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 11.5px;
  transition: var(--transition-smooth);
}

.cbt-results-close-btn:hover {
  background: rgba(255,255,255,0.08);
}

.cbt-results-summary-row {
  display: flex;
  gap: 20px;
  align-items: stretch;
}

.cbt-results-total-box {
  width: 200px;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 20px 14px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  flex-shrink: 0;
}

.summary-label {
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.score-display {
  display: flex;
  align-items: baseline;
  margin-bottom: 10px;
}

.score-num {
  font-size: 38px;
  font-weight: 700;
  color: #e9d5ff;
}

.score-max {
  font-size: 13px;
  color: var(--text-muted);
  margin-left: 2px;
}

.pass-status-badge {
  padding: 3px 14px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 700;
}

.pass-status-badge.pass {
  background: rgba(16, 185, 129, 0.12);
  border: 1px solid rgba(16, 185, 129, 0.35);
  color: var(--success-color);
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.15);
}

.pass-status-badge.fail {
  background: rgba(239, 68, 68, 0.12);
  border: 1px solid rgba(239, 68, 68, 0.35);
  color: #f87171;
  box-shadow: 0 0 10px rgba(239, 68, 68, 0.15);
}

.cbt-results-fields-box {
  flex: 1;
  background: rgba(0, 0, 0, 0.2);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 16px 20px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 10px;
}

.field-score-item {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.field-score-meta {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
}

.field-score-meta strong {
  color: var(--text-main);
}

.field-score-meta span {
  font-family: 'Fira Code', monospace;
  color: var(--text-muted);
}

.field-score-progressbar {
  height: 5px;
  background: rgba(255,255,255,0.04);
  border-radius: 3px;
  overflow: hidden;
}

.field-score-fill {
  height: 100%;
  background: linear-gradient(90deg, #7c3aed, #a78bfa);
  border-radius: 3px;
}

.field-score-status {
  font-size: 10.5px;
  color: var(--text-muted);
  text-align: right;
}

.cbt-results-details-wrapper {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.cbt-results-details-wrapper h3 {
  font-size: 15px;
  color: #e9d5ff;
  font-weight: 600;
}

.results-table-tip {
  font-size: 11.5px;
  color: var(--text-muted);
}

.results-table-container {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  overflow: hidden;
}

.results-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 12px;
  text-align: left;
}

.results-table th {
  background: rgba(255,255,255,0.02);
  padding: 8px 12px;
  font-weight: 600;
  border-bottom: 1px solid var(--border-color);
  color: #c084fc;
}

.results-table td {
  padding: 8px 12px;
  border-bottom: 1px solid rgba(255,255,255,0.02);
  color: var(--text-main);
}

.results-table tbody tr {
  cursor: pointer;
  transition: var(--transition-smooth);
}

.results-table tbody tr:hover {
  background: rgba(255,255,255,0.02);
}

.results-table td i.correct {
  color: var(--success-color);
}

.results-table td i.incorrect {
  color: #ef4444;
}

/* Expansion Review Drawer in Report Table */
.results-review-expansion-row {
  background: rgba(0, 0, 0, 0.25) !important;
}

.results-review-card-expansion {
  padding: 12px 20px;
  border-bottom: 1px solid rgba(168, 85, 247, 0.2);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.review-q-title {
  font-size: 13px;
  font-weight: 700;
  color: #e9d5ff;
}

.review-q-text {
  font-size: 13px;
  line-height: 1.5;
  color: var(--text-main);
}

.review-q-choices-panel {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 6px;
  margin: 6px 0;
}

.review-choice-item-box {
  background: rgba(0,0,0,0.15);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 12px;
  display: flex;
  gap: 6px;
}

.review-choice-item-box.correct {
  border-color: rgba(52, 211, 153, 0.35);
  background: rgba(52, 211, 153, 0.03);
  color: #a7f3d0;
}

.review-choice-item-box.incorrect {
  border-color: rgba(239, 68, 68, 0.35);
  background: rgba(239, 68, 68, 0.03);
  color: #fca5a5;
}

.review-choice-badge {
  font-weight: 700;
  color: var(--text-muted);
}

.review-choice-item-box.correct .review-choice-badge {
  color: var(--success-color);
}

.review-choice-item-box.incorrect .review-choice-badge {
  color: #f87171;
}

.review-kaisetsu-box {
  background: rgba(168, 85, 247, 0.02);
  border: 1px solid rgba(168, 85, 247, 0.2);
  border-radius: 8px;
  padding: 12px;
}

.review-kaisetsu-box h4 {
  font-size: 12px;
  font-weight: 700;
  color: #c084fc;
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 4px;
}

.review-kaisetsu-text {
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--text-main);
}

.review-kaisetsu-text p {
  margin-bottom: 6px;
}

.review-kaisetsu-text table {
  margin: 8px 0;
  border-collapse: collapse;
}

.review-kaisetsu-text th, .review-kaisetsu-text td {
  border: 1px solid var(--border-color);
  padding: 4px 8px;
  font-size: 11.5px;
}

/* Slide progress header quiz navigation for Chapter lessons */
.quiz-nav-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  background: rgba(0, 0, 0, 0.15);
  padding: 4px 10px;
  border-radius: 6px;
  margin-bottom: 10px;
  border: 1px solid var(--border-color);
}

.quiz-nav-text {
  font-size: 11.5px;
  font-weight: 600;
  color: #c084fc;
}

.quiz-nav-buttons {
  display: flex;
  gap: 4px;
}

.quiz-nav-btn {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.08);
  color: var(--text-main);
  padding: 1px 6px;
  border-radius: 4px;
  font-size: 10.5px;
  cursor: pointer;
  transition: var(--transition-smooth);
}

.quiz-nav-btn:hover {
  background: rgba(255, 255, 255, 0.06);
}

/* PDF Textbook button styles */
.sidebar-pdf-container {
  margin-top: auto;
  padding: 12px;
  border-top: 1px solid var(--border-color);
  background: rgba(0, 0, 0, 0.15);
}

.sidebar-pdf-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 100%;
  padding: 10px;
  background: linear-gradient(135deg, rgba(239, 68, 68, 0.15), rgba(220, 38, 38, 0.15));
  border: 1px dashed rgba(239, 68, 68, 0.4);
  color: #f87171 !important;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: var(--transition-smooth);
}

.sidebar-pdf-btn:hover {
  background: linear-gradient(135deg, rgba(239, 68, 68, 0.25), rgba(220, 38, 38, 0.25));
  border-color: #ef4444;
  box-shadow: 0 0 10px rgba(239, 68, 68, 0.15);
  transform: translateY(-1px);
}

/* Sidebar Collapsible Accordion for IT Passport Chapters */
.sidebar-chapter-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 12px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.04);
  border-radius: 8px;
  cursor: pointer;
  margin-top: 10px;
  margin-bottom: 4px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-main);
  transition: var(--transition-smooth);
}

.sidebar-chapter-header:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: rgba(255, 255, 255, 0.1);
}

.sidebar-chapter-header.active-parent {
  border-left: 3px solid var(--neon-purple);
}

.chapter-header-title {
  display: flex;
  align-items: center;
  gap: 8px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chapter-arrow {
  font-size: 11px;
  color: var(--text-muted);
  transition: transform 0.25s ease;
}

.sidebar-chapter-header.expanded .chapter-arrow {
  transform: rotate(90deg);
  color: var(--neon-purple);
}

.chapter-progress-badge {
  font-size: 10.5px;
  background: rgba(168, 85, 247, 0.15);
  color: #c084fc;
  padding: 2px 6px;
  border-radius: 4px;
  font-weight: 550;
  white-space: nowrap;
}

/* Sidebar Chapter Body containing sub-sections */
.sidebar-chapter-body {
  padding-left: 12px;
  margin-bottom: 12px;
  border-left: 1px dashed rgba(255, 255, 255, 0.08);
  margin-left: 16px;
  display: none; /* Controlled by JS */
}

/* Specific styling adjustments for sub-items in chapter body */
.sidebar-chapter-body .lesson-nav-item {
  margin-bottom: 2px;
  font-size: 12.5px;
  border-radius: 6px;
  padding: 8px 10px;
  background: transparent;
}

.sidebar-chapter-body .lesson-nav-item.active {
  background: var(--neon-purple-glow);
  border-color: rgba(168, 85, 247, 0.3);
  color: #d8b4fe;
}

.sidebar-chapter-body .lesson-nav-item.completed {
  background: rgba(16, 185, 129, 0.02);
}

.sidebar-chapter-body .lesson-nav-item.completed:hover {
  background: rgba(16, 185, 129, 0.05);
}

/* Sidebar Collapsible Accordion for Subsections (Level 2 collapsible) */
.sidebar-subsection-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 6px 8px;
  background: rgba(255, 255, 255, 0.01);
  border: 1px solid rgba(255, 255, 255, 0.02);
  border-radius: 6px;
  cursor: pointer;
  margin-top: 6px;
  margin-bottom: 2px;
  font-size: 12px;
  font-weight: 550;
  color: var(--text-main);
  transition: var(--transition-smooth);
}

.sidebar-subsection-header:hover {
  background: rgba(255, 255, 255, 0.03);
  border-color: rgba(255, 255, 255, 0.06);
}

.sidebar-subsection-header.active-parent {
  border-left: 2px solid var(--neon-purple);
}

.subsection-header-title {
  display: flex;
  align-items: center;
  gap: 6px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.subsection-arrow {
  font-size: 10px;
  color: var(--text-muted);
  transition: transform 0.25s ease;
}

.sidebar-subsection-header.expanded .subsection-arrow {
  transform: rotate(90deg);
  color: var(--neon-purple);
}

.subsection-progress-badge {
  font-size: 10px;
  background: rgba(168, 85, 247, 0.15);
  color: #d8b4fe;
  padding: 1px 4px;
  border-radius: 3px;
  font-weight: 500;
  white-space: nowrap;
}

.sidebar-subsection-body {
  padding-left: 10px;
  margin-bottom: 8px;
  border-left: 1px dashed rgba(255, 255, 255, 0.05);
  margin-left: 12px;
  display: none; /* Controlled by JS */
}

/* Specific styling for the third level lessons */
.sidebar-subsection-body .lesson-nav-item {
  margin-bottom: 2px;
  font-size: 11.5px;
  border-radius: 5px;
  padding: 6px 8px;
  background: transparent;
}

.sidebar-subsection-body .lesson-nav-item.active {
  background: var(--neon-purple-glow);
  border-color: rgba(168, 85, 247, 0.3);
  color: #d8b4fe;
}

.sidebar-subsection-body .lesson-nav-item.completed {
  background: rgba(16, 185, 129, 0.02);
}

.sidebar-subsection-body .lesson-nav-item.completed:hover {
  background: rgba(16, 185, 129, 0.05);
}

/* Locate in PDF Header Button */
.lesson-header-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}

.locate-pdf-btn {
  background: linear-gradient(135deg, rgba(239, 68, 68, 0.12), rgba(220, 38, 38, 0.12));
  border: 1px solid rgba(239, 68, 68, 0.3);
  color: #fca5a5;
  padding: 4px 10px;
  border-radius: 6px;
  font-size: 11px;
  font-weight: 550;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}

.locate-pdf-btn:hover {
  background: linear-gradient(135deg, rgba(239, 68, 68, 0.22), rgba(220, 38, 38, 0.22));
  border-color: rgba(239, 68, 68, 0.55);
  box-shadow: 0 0 10px rgba(239, 68, 68, 0.25);
  color: #fee2e2;
}

.locate-pdf-btn i {
  font-size: 12px;
}

/* Embedded PDF Overlay Viewer Styles */
.lesson-content {
  position: relative; /* Required for absolute overlay positioning */
}

.lesson-content.pdf-active {
  overflow-y: hidden !important; /* Prevent parent scrolling when PDF is open */
}

.pdf-viewer-panel {
  position: absolute;
  top: 20px;
  left: 20px;
  right: 20px;
  bottom: 20px;
  z-index: 500;
  background: rgba(18, 24, 36, 0.85); /* Slightly darker backing for overlay contrast */
  backdrop-filter: blur(20px);
  border: 1px solid var(--border-color-glow); /* Cyan accent glow border for visual cue */
  border-radius: 8px;
  box-shadow: 0 12px 48px rgba(0, 0, 0, 0.6);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  animation: modalPop 0.28s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.pdf-panel-header {
  padding: 14px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 14px;
  font-weight: 600;
  color: var(--neon-cyan);
  border-bottom: 1px solid var(--border-color);
  background: rgba(0, 0, 0, 0.3);
}

.pdf-close-btn {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--text-muted);
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}

.pdf-close-btn:hover {
  border-color: var(--error-color);
  color: var(--error-color);
  box-shadow: 0 0 8px var(--error-glow);
  transform: translateY(-1px);
}

.pdf-iframe-container {
  flex: 1;
  width: 100%;
  height: 100%;
  background: #1e1e1e;
}

#embedded-pdf-iframe {
  width: 100%;
  height: 100%;
  border: none;
  background: #1e1e1e;
}

@keyframes modalPop {
  from {
    opacity: 0;
    transform: scale(0.96) translateY(12px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

/* ================================================================
   JAVA SECTION THEME — Java Orange (#f89820) color scheme
   ================================================================ */

:root {
  --java-orange: hsl(245, 95%, 68%);
  --java-orange-dim: hsla(245, 95%, 68%, 0.15);
  --java-orange-glow: hsla(245, 95%, 68%, 0.35);
  --java-dark: #090b11;
  --java-editor-bg: #0b0f19;
  --java-editor-line: rgba(99, 102, 241, 0.08);
}

/* Java subject tab */
#subject-tab-java:hover,
#subject-tab-java.active {
  background: var(--java-orange-dim);
  border-color: var(--java-orange);
  box-shadow: 0 0 12px var(--java-orange-glow);
  color: var(--java-orange);
}

/* Java sub-header tabs */
#java-sub-header .sub-header-tab.active {
  background: var(--java-orange-dim);
  border-color: var(--java-orange);
  color: var(--java-orange);
}

/* Hide/show widgets by subject mode */
.java-widget { display: none; }
body.mode-java .java-widget { display: flex; flex-direction: column; }
body.mode-java .sql-widget { display: none !important; }
body.mode-java .itpass-widget { display: none !important; }
body.mode-java #header-challenge { display: none !important; }

/* Java progress badge */
.lesson-badge.java-badge {
  background: var(--java-orange-dim);
  border: 1px solid var(--java-orange);
  color: var(--java-orange);
}

/* ── Java Sandbox Card ── */
.java-sandbox-card {
  flex: 1.4;
  min-height: 280px;
  flex-direction: column !important;
  padding: 0 !important;
  overflow: hidden;
  border: 1px solid var(--java-orange);
  box-shadow: 0 0 16px var(--java-orange-glow), inset 0 0 40px rgba(99,102,241,0.03);
}

.java-sandbox-header {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 10px 14px 8px;
  background: linear-gradient(135deg, rgba(99,102,241,0.12), rgba(99,102,241,0.04));
  border-bottom: 1px solid rgba(99,102,241,0.25);
}

.java-sandbox-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 600;
  color: var(--java-orange);
}

.java-sandbox-title i {
  font-size: 18px;
}

.java-sandbox-lesson-label {
  font-size: 11px;
  color: var(--text-muted);
  font-style: italic;
}

.java-sandbox-body {
  display: flex;
  flex-direction: column;
  gap: 0;
  flex: 1;
  min-height: 0;
}

/* ── Editor Panel ── */
.java-editor-panel {
  display: flex;
  flex-direction: column;
  border-bottom: 1px solid rgba(99,102,241,0.2);
  flex: 1;
  min-height: 0;
}

.java-editor-toolbar {
  display: flex;
  gap: 6px;
  padding: 6px 10px;
  background: rgba(13,17,23,0.8);
  border-bottom: 1px solid var(--border-color);
}

.java-tool-btn {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 4px 10px;
  font-size: 11px;
  font-weight: 500;
  border: 1px solid rgba(99,102,241,0.3);
  background: rgba(99,102,241,0.08);
  color: var(--java-orange);
  border-radius: 4px;
  cursor: pointer;
  transition: all 0.2s;
  font-family: inherit;
}

.java-tool-btn:hover {
  background: rgba(99,102,241,0.2);
  border-color: var(--java-orange);
}

.java-tool-btn.danger {
  border-color: rgba(239,68,68,0.3);
  background: rgba(239,68,68,0.08);
  color: hsl(0,80%,65%);
}
.java-tool-btn.danger:hover {
  background: rgba(239,68,68,0.2);
  border-color: hsl(0,80%,55%);
}

.java-editor-container {
  display: flex;
  flex-direction: row;
  flex: 1;
  min-height: 120px;
  background: var(--java-editor-bg);
  overflow: hidden;
}

.java-line-numbers {
  display: flex;
  flex-direction: column;
  padding: 10px 8px;
  background: rgba(99,102,241,0.05);
  border-right: 1px solid rgba(99,102,241,0.15);
  min-width: 36px;
  text-align: right;
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  line-height: 1.6;
  color: rgba(99,102,241,0.5);
  overflow: hidden;
  user-select: none;
  gap: 0;
}

.java-line-numbers span {
  display: block;
  line-height: 1.6;
}

.java-editor {
  flex: 1;
  background: transparent;
  color: #e6edf3;
  font-family: 'Fira Code', 'Consolas', monospace;
  font-size: 12.5px;
  line-height: 1.6;
  padding: 10px 12px;
  border: none;
  outline: none;
  resize: none;
  tab-size: 4;
  overflow-y: auto;
  overflow-x: auto;
  white-space: pre;
}

.java-editor::placeholder {
  color: rgba(99,102,241,0.3);
}

/* ── Output Panel ── */
.java-output-panel {
  display: flex;
  flex-direction: column;
  min-height: 120px;
  max-height: 200px;
}

.java-output-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 12px;
  background: rgba(13,17,23,0.8);
  border-bottom: 1px solid var(--border-color);
  font-size: 12px;
  color: var(--text-muted);
}

.java-sandbox-status {
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 10px;
  font-weight: 500;
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  transition: all 0.3s;
}

.java-status-running { background: rgba(99,102,241,0.15); border-color: var(--java-orange); color: var(--java-orange); }
.java-status-success { background: rgba(34,197,94,0.15); border-color: #22c55e; color: #4ade80; }
.java-status-error   { background: rgba(239,68,68,0.15); border-color: #ef4444; color: #f87171; }
.java-status-idle    { background: rgba(255,255,255,0.05); color: var(--text-muted); }

.java-output-content {
  flex: 1;
  margin: 0;
  padding: 10px 14px;
  background: #050810;
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  line-height: 1.6;
  color: #a8d9a8;
  overflow-y: auto;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
}

.java-output-success { color: #86efac; }
.java-output-error   { color: #fca5a5; }

/* ── Run Bar ── */
.java-run-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 12px;
  background: rgba(99,102,241,0.06);
  border-top: 1px solid rgba(99,102,241,0.2);
  gap: 8px;
}

.java-run-info {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 10.5px;
  color: rgba(99,102,241,0.6);
}

.java-run-btn {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 7px 18px;
  background: linear-gradient(135deg, var(--java-orange), hsl(25,90%,45%));
  color: #fff;
  border: none;
  border-radius: 6px;
  font-weight: 700;
  font-size: 13px;
  cursor: pointer;
  transition: all 0.2s;
  box-shadow: 0 0 12px var(--java-orange-glow);
  font-family: inherit;
  white-space: nowrap;
  animation: pulse-glow-orange 3s infinite ease-in-out;
}

.java-run-btn:hover:not(:disabled) {
  background: linear-gradient(135deg, hsl(33,100%,65%), hsl(25,95%,50%));
  box-shadow: 0 0 22px rgba(99, 102, 241, 0.85), 0 0 35px rgba(129, 140, 248, 0.45);
  transform: translateY(-1px);
}

.java-run-btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.java-run-btn kbd {
  font-size: 10px;
  background: rgba(255,255,255,0.2);
  padding: 1px 5px;
  border-radius: 3px;
  border: 1px solid rgba(255,255,255,0.3);
}

.sandbox-btn-icon {
  font-size: 14px;
}

/* ── Input Panel ── */
.java-input-panel {
  display: flex;
  flex-direction: column;
  border-bottom: 1px solid rgba(99,102,241,0.15);
  background: rgba(13, 17, 23, 0.4);
}

.java-input-header {
  display: flex;
  align-items: center;
  padding: 4px 12px;
  background: rgba(13, 17, 23, 0.7);
  border-bottom: 1px solid rgba(99,102,241,0.1);
  font-size: 11px;
  color: var(--text-muted);
}

.java-input-row {
  display: flex;
  flex-direction: row;
  background: #06090f;
  padding: 6px 12px;
  gap: 12px;
  align-items: center;
}

.java-input-content {
  flex: 1;
  margin: 0;
  padding: 4px 0;
  background: transparent;
  color: #e6edf3;
  font-family: 'Fira Code', 'Consolas', monospace;
  font-size: 12px;
  border: none;
  outline: none;
  resize: none;
  height: 54px;
}

.java-input-content::placeholder {
  color: rgba(99, 102, 241, 0.25);
  font-style: italic;
}

.java-input-sidebar {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 6px;
  flex-shrink: 0;
}

.java-run-info-mini {
  font-size: 10px;
  color: rgba(99, 102, 241, 0.6);
  font-family: 'Outfit', sans-serif;
  text-align: right;
  white-space: nowrap;
}

.java-input-sidebar .java-run-btn {
  padding: 6px 14px;
  font-size: 12px;
  box-shadow: 0 0 8px var(--java-orange-glow);
}

/* ── Java Standalone Output Card ── */
#java-output-card {
  border: 1px solid var(--java-orange);
  box-shadow: 0 0 16px var(--java-orange-glow);
}

.java-output-header {
  border-bottom: 1px solid rgba(99, 102, 241, 0.25) !important;
  color: var(--java-orange) !important;
}

#java-output-card.maximized {
  border-color: var(--java-orange) !important;
  box-shadow: 0 0 60px rgba(99, 102, 241, 0.3), 0 24px 80px rgba(0,0,0,0.8) !important;
}

/* ── Java Vocab Flashcard (in main content area) ── */
.java-vocab-section {
  background: rgba(99,102,241,0.06);
  border: 1px solid rgba(99,102,241,0.25);
  border-radius: 12px;
  padding: 12px;
  margin-top: 4px;
  flex-direction: column;
  gap: 10px;
}

.java-vocab-header {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 600;
  color: var(--java-orange);
  flex-wrap: wrap;
}

.java-vocab-flip-btn,
.java-vocab-nav-btn {
  padding: 3px 10px;
  border: 1px solid rgba(99,102,241,0.4);
  background: rgba(99,102,241,0.1);
  color: var(--java-orange);
  border-radius: 5px;
  cursor: pointer;
  font-size: 12px;
  font-family: inherit;
  transition: all 0.2s;
}

.java-vocab-flip-btn:hover,
.java-vocab-nav-btn:hover {
  background: rgba(99,102,241,0.25);
}

.java-vocab-counter {
  margin-left: auto;
  font-size: 11px;
  color: var(--text-muted);
}

/* 3D Flip Card */
.java-flashcard-wrapper {
  perspective: 800px;
  cursor: pointer;
  min-height: 110px;
}

.java-flashcard {
  width: 100%;
  min-height: 110px;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.java-flashcard.flipped {
  transform: rotateY(180deg);
}

.java-flashcard-front,
.java-flashcard-back {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  border-radius: 10px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 16px;
  text-align: center;
  gap: 8px;
}

.java-flashcard-front {
  background: linear-gradient(135deg, rgba(99,102,241,0.12), rgba(79,70,229,0.08));
  border: 1px solid rgba(99,102,241,0.35);
}

.java-flashcard-back {
  background: linear-gradient(135deg, rgba(34,197,94,0.1), rgba(16,185,129,0.06));
  border: 1px solid rgba(34,197,94,0.3);
  transform: rotateY(180deg);
}

.java-card-term {
  font-size: 18px;
  font-weight: 700;
  color: var(--java-orange);
  font-family: 'Fira Code', monospace;
}

.java-card-hint {
  font-size: 10px;
  color: var(--text-muted);
  opacity: 0.7;
}

.java-card-zh {
  font-size: 20px;
  font-weight: 700;
  color: #4ade80;
}

.java-card-desc {
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.5;
}

/* ── Sidebar: Java book groups ── */
.java-sidebar-group {
  margin-bottom: 4px;
}

.java-sidebar-group-header {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 10px;
  font-size: 11px;
  font-weight: 700;
  color: var(--java-orange);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  opacity: 0.9;
  cursor: pointer;
  border-radius: 6px;
  transition: background 0.2s;
}

.java-sidebar-group-header:hover {
  background: rgba(99,102,241,0.08);
}

.lesson-nav-item.java-item.active {
  border-color: var(--java-orange);
  background: rgba(99,102,241,0.12);
  box-shadow: inset 2px 0 0 var(--java-orange), 0 0 8px rgba(99,102,241,0.1);
}

.lesson-nav-item.java-item .lesson-number {
  background: rgba(99,102,241,0.15);
  color: var(--java-orange);
}

.lesson-nav-item.java-item.completed .lesson-number::after {
  color: #4ade80;
}


/* ── Java Sandbox Editor Syntax Highlighting Overlay ── */
.java-editor-wrapper {
  position: relative;
  flex: 1;
  height: 100%;
}

.java-editor {
  position: absolute !important;
  top: 0;
  left: 0;
  width: 100% !important;
  height: 100% !important;
  background: transparent !important;
  color: transparent !important; /* Hide plain text under editor */
  caret-color: #e6edf3 !important; /* Make sure blinking cursor remains visible */
  z-index: 2;
  resize: none;
  overflow: auto;
  white-space: pre;
}

.java-editor::placeholder {
  color: rgba(99, 102, 241, 0.3) !important;
  -webkit-text-fill-color: rgba(99, 102, 241, 0.3) !important;
  opacity: 1 !important;
}

.java-highlight-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 10px 12px;
  background: transparent;
  color: #e6edf3;
  font-family: 'Fira Code', 'Consolas', monospace;
  font-size: 12.5px;
  line-height: 1.6;
  pointer-events: none; /* Click passes through directly to textarea */
  z-index: 1;
  overflow: hidden;
  white-space: pre;
  box-sizing: border-box;
}

/* Java Code Color Syntax Tokens */
.hl-keyword {
  color: var(--java-orange) !important;
  font-weight: 700;
}
.hl-sys {
  color: #7dd3fc !important; /* light sky blue standard API */
}
.hl-string {
  color: #a7f3d0 !important; /* light green string values */
}
.hl-comment {
  color: #64748b !important; /* gray-blue comment block */
  font-style: italic;
}
.hl-number {
  color: #fdba74 !important; /* light peach digits */
}

/* Java Accordion Custom Theme Overrides */
.sidebar-chapter-header.java-chapter-header.active-parent {
  border-left-color: var(--java-orange);
}
.sidebar-chapter-header.java-chapter-header.expanded .chapter-arrow {
  color: var(--java-orange);
}
.java-chapter-body .lesson-nav-item.active {
  background: var(--java-orange-dim);
  border-color: rgba(99, 102, 241, 0.3);
  color: #ffedd5;
}
.java-chapter-body .lesson-nav-item.completed {
  background: rgba(99, 102, 241, 0.01);
}
.java-chapter-body .lesson-nav-item.completed:hover {
  background: rgba(99, 102, 241, 0.04);
}
.java-progress-badge {
  background: var(--java-orange-dim);
  color: var(--java-orange);
}

/* ===================================================
   SG (Information Security Management) Emerald Theme
   =================================================== */
:root {
  --neon-sg-teal: hsl(160, 100%, 45%);
  --neon-sg-teal-glow: hsla(160, 100%, 45%, 0.15);
  --neon-sg-teal-dim: hsla(160, 100%, 45%, 0.05);
}

body.mode-sg {
  background-image: 
    radial-gradient(circle at 10% 20%, rgba(16, 185, 129, 0.08) 0%, transparent 40%),
    radial-gradient(circle at 90% 80%, rgba(4, 120, 87, 0.06) 0%, transparent 40%);
}

#subject-tab-sg.active {
  background: var(--neon-sg-teal-glow);
  color: var(--neon-sg-teal);
  border-color: rgba(16, 185, 129, 0.3);
  box-shadow: 0 0 10px rgba(16, 185, 129, 0.2);
}

body.mode-sg .lesson-nav-item.active {
  background: var(--neon-sg-teal-glow);
  color: var(--text-main);
  border-color: rgba(16, 185, 129, 0.3);
}

body.mode-sg .sidebar-title {
  color: var(--neon-sg-teal);
}

body.mode-sg .lesson-badge {
  background: rgba(16, 185, 129, 0.1);
  color: var(--neon-sg-teal);
  border: 1px solid rgba(16, 185, 129, 0.2);
}

body.mode-sg .vocab-highlight {
  color: var(--neon-sg-teal);
  background: rgba(16, 185, 129, 0.05);
  border-bottom: 1px dashed var(--neon-sg-teal);
}

body.mode-sg .sub-header-tab.active {
  border-bottom-color: var(--neon-sg-teal);
  color: var(--neon-sg-teal);
}

body.mode-sg .progress-info strong {
  color: var(--neon-sg-teal);
}

body.mode-sg .progress-bar-fill {
  background: linear-gradient(90deg, hsl(160, 80%, 40%), var(--neon-sg-teal));
  box-shadow: 0 0 8px var(--neon-sg-teal);
}

body.mode-sg .quiz-option.selected {
  border-color: var(--neon-sg-teal);
  background: var(--neon-sg-teal-glow);
}

body.mode-sg .quiz-option.selected .option-marker {
  background: var(--neon-sg-teal);
  color: #fff;
}

body.mode-sg .quiz-submit-btn {
  background: linear-gradient(135deg, hsl(160, 80%, 40%), var(--neon-sg-teal));
}

body.mode-sg .quiz-submit-btn:hover {
  box-shadow: 0 0 15px rgba(16, 185, 129, 0.4);
}

body.mode-sg .cbt-indicator-badge {
  background: var(--neon-sg-teal-glow);
  color: var(--neon-sg-teal);
  border: 1px solid rgba(16, 185, 129, 0.2);
}

body.mode-sg .cbt-option-item.selected {
  border-color: var(--neon-sg-teal);
  background: var(--neon-sg-teal-glow);
}

body.mode-sg .cbt-option-item.selected .cbt-option-badge {
  background: var(--neon-sg-teal);
  color: #fff;
}

body.mode-sg .cbt-grid-btn.active {
  background: var(--neon-sg-teal);
  border-color: var(--neon-sg-teal);
}

body.mode-sg .cbt-grid-btn.flagged {
  border-color: #fbbf24;
}

body.mode-sg .cbt-grid-btn.flagged::after {
  color: #fbbf24;
}

/* Specific styling for Subject B content */
.select-images {
  margin-top: 12px;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 12px;
  display: flex;
  justify-content: center;
}

.select-images img {
  max-width: 100%;
  height: auto;
  border-radius: 4px;
}

/* ==========================================================================
   PYTHON WIDGETS & THEME STYLING
   ========================================================================== */

:root {
  --python-blue: #306998;
  --python-blue-dim: rgba(48, 105, 152, 0.12);
  --python-blue-glow: rgba(48, 105, 152, 0.3);
  --python-yellow: #ffd43b;
  --python-yellow-dim: rgba(255, 212, 59, 0.15);
  --python-yellow-glow: rgba(255, 212, 59, 0.3);
  --python-dark: #0a111b;
  --python-editor-bg: #0b0f19;
  --python-editor-line: rgba(255, 212, 59, 0.06);
}

.python-widget { display: none; }
body.mode-python .python-widget { display: flex; flex-direction: column; }
body.mode-python {
  --neon-cyan: #00f2fe;
  --python-blue: #00f2fe;
  --python-blue-dim: rgba(0, 242, 254, 0.12);
  --python-blue-glow: rgba(0, 242, 254, 0.35);
  --python-yellow: #00a8ff;
  --python-yellow-dim: rgba(0, 168, 255, 0.15);
  --python-yellow-glow: rgba(0, 168, 255, 0.35);
  --python-editor-line: rgba(0, 242, 254, 0.08);
}


#subject-tab-python.active {
  background: linear-gradient(135deg, var(--python-blue-dim), var(--python-yellow-dim));
  border: 1px solid var(--python-blue-glow);
  color: var(--python-yellow);
  box-shadow: 0 0 10px var(--python-yellow-glow);
}

.lesson-badge.python-badge {
  background: var(--python-blue-dim);
  border: 1px solid var(--python-blue);
  color: var(--python-yellow);
}

.python-sandbox-card {
  flex: 1.3;
  display: flex;
  flex-direction: column;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: border-color 0.3s, box-shadow 0.3s;
}

body.mode-python .python-sandbox-card:focus-within {
  border-color: var(--python-blue);
  box-shadow: 0 0 16px var(--python-blue-glow);
}

.python-sandbox-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 16px;
  background: rgba(255, 255, 255, 0.02);
  border-bottom: 1px solid var(--border-color);
}

.python-sandbox-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-main);
}

.python-sandbox-title i {
  color: var(--python-yellow);
  font-size: 15px;
}

.python-sandbox-lesson-label {
  font-size: 11px;
  color: var(--text-muted);
}

.python-sandbox-body {
  display: flex;
  flex-direction: column;
  flex: 1;
  overflow: hidden;
}

.python-editor-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  border-bottom: 1px solid var(--border-color);
  min-height: 120px;
}

.python-editor-toolbar {
  display: flex;
  justify-content: flex-end;
  gap: 8px;
  padding: 4px 12px;
  background: rgba(255, 255, 255, 0.01);
  border-bottom: 1px solid rgba(255, 255, 255, 0.03);
}

.python-tool-btn {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  font-size: 11px;
  font-weight: 500;
  padding: 3px 8px;
  border-radius: 4px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: var(--transition-smooth);
}

.python-tool-btn:hover {
  color: var(--python-yellow);
  background: rgba(255, 255, 255, 0.04);
}

.python-tool-btn.danger:hover {
  color: #ef4444;
  background: rgba(239, 68, 68, 0.05);
}

.python-editor-container {
  display: flex;
  flex: 1;
  overflow: hidden;
  background: var(--python-editor-bg);
  position: relative;
}

.python-line-numbers {
  display: flex;
  flex-direction: column;
  width: 38px;
  padding: 12px 0;
  text-align: right;
  background: rgba(0, 0, 0, 0.15);
  border-right: 1px solid rgba(255, 255, 255, 0.05);
  color: rgba(255, 255, 255, 0.25);
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  line-height: 19px;
  user-select: none;
  overflow: hidden;
}

.python-line-numbers span {
  padding-right: 8px;
}

.python-editor-wrapper {
  position: relative;
  flex: 1;
  height: 100%;
  overflow: hidden;
}

.python-highlight-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 12px;
  margin: 0;
  color: var(--text-main);
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  line-height: 19px;
  white-space: pre;
  overflow: auto;
  pointer-events: none;
  box-sizing: border-box;
  background: transparent;
  border: none;
  z-index: 1;
}

.python-editor {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 12px;
  margin: 0;
  background: transparent;
  color: transparent;
  caret-color: var(--text-main);
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  line-height: 19px;
  width: 100%;
  height: 100%;
  border: none;
  resize: none;
  outline: none;
  white-space: pre;
  overflow: auto;
  box-sizing: border-box;
  z-index: 2;
}

.python-editor::placeholder {
  color: var(--text-muted);
}

.python-input-panel {
  height: 110px;
  display: flex;
  flex-direction: column;
  background: rgba(0, 0, 0, 0.15);
  border-top: 1px solid var(--border-color);
}

.python-input-header {
  padding: 4px 12px;
  font-size: 11px;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border-color);
  background: rgba(255, 255, 255, 0.01);
}

.python-input-row {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.python-input-content {
  flex: 1;
  background: transparent;
  border: none;
  outline: none;
  resize: none;
  padding: 8px 12px;
  color: var(--text-main);
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  line-height: 1.5;
  box-sizing: border-box;
}

.python-input-content::placeholder {
  color: rgba(255, 255, 255, 0.15);
}

.python-input-sidebar {
  width: 125px;
  border-left: 1px solid var(--border-color);
  padding: 8px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  background: rgba(0, 0, 0, 0.05);
}

.python-run-info-mini {
  font-size: 10px;
  color: var(--text-muted);
  text-align: center;
}

.python-run-btn {
  background: linear-gradient(135deg, #00f2fe, #0088ff);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: #030712;
  border-radius: 6px;
  padding: 8px;
  font-size: 12px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  box-shadow: 0 0 10px rgba(0, 242, 254, 0.4);
  transition: var(--transition-smooth);
  animation: pulse-glow 3s infinite ease-in-out;
}

.python-run-btn:hover:not(:disabled) {
  opacity: 1;
  box-shadow: 0 0 20px rgba(0, 242, 254, 0.8), 0 0 30px rgba(0, 136, 255, 0.4);
  transform: translateY(-1px);
}


.python-run-btn:disabled {
  background: var(--border-color);
  color: var(--text-muted);
  cursor: not-allowed;
  box-shadow: none;
}

.python-run-btn kbd {
  font-size: 9px;
  background: rgba(0,0,0,0.2);
  padding: 1px 3px;
  border-radius: 3px;
}

.python-sandbox-status {
  font-size: 11px;
  padding: 3px 8px;
  border-radius: 4px;
  border: 1px solid transparent;
  font-weight: 600;
}

.python-status-running { background: rgba(48,105,152,0.15); border-color: var(--python-blue); color: var(--python-yellow); }
.python-status-success { background: rgba(34,197,94,0.15); border-color: #22c55e; color: #4ade80; }
.python-status-error   { background: rgba(239,68,68,0.15); border-color: #ef4444; color: #f87171; }
.python-status-idle    { background: rgba(255,255,255,0.05); color: var(--text-muted); }

.python-output-content {
  margin: 0;
  padding: 12px;
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  line-height: 1.6;
  white-space: pre-wrap;
  color: var(--text-muted);
  box-sizing: border-box;
}

.python-output-success { color: #86efac; }
.python-output-error   { color: #fca5a5; }

/* Python Vocab Section styles */
.python-vocab-section {
  display: none;
  flex-direction: column;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 12px;
  margin-top: 16px;
  box-shadow: var(--shadow-sm);
}

.python-vocab-header {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 8px;
}

.python-vocab-header i {
  color: var(--python-yellow);
}

.python-vocab-flip-btn,
.python-vocab-nav-btn {
  background: rgba(255,255,255,0.02);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  font-size: 10px;
  padding: 2px 6px;
  border-radius: 4px;
  cursor: pointer;
  transition: var(--transition-smooth);
}

.python-vocab-flip-btn {
  margin-left: auto;
}

.python-vocab-flip-btn:hover,
.python-vocab-nav-btn:hover {
  color: var(--python-yellow);
  border-color: var(--python-yellow);
}

.python-vocab-counter {
  font-size: 10px;
  color: var(--text-muted);
  margin: 0 4px;
}

.python-flashcard-wrapper {
  perspective: 1000px;
  width: 100%;
  height: 90px;
  cursor: pointer;
}

.python-flashcard {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

.python-flashcard.flipped {
  transform: rotateY(180deg);
}

.python-flashcard-front,
.python-flashcard-back {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: 6px;
  padding: 10px;
  box-sizing: border-box;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.python-flashcard-front {
  background: rgba(48,105,152,0.06);
  border: 1px solid var(--python-blue-glow);
}

.python-flashcard-back {
  background: rgba(255,212,59,0.04);
  border: 1px solid var(--python-yellow-glow);
  transform: rotateY(180deg);
}

.python-card-term {
  font-size: 15px;
  font-weight: 700;
  color: var(--python-yellow);
  text-align: center;
}

.python-card-hint {
  font-size: 9px;
  color: var(--text-muted);
  margin-top: 4px;
}

.python-card-zh {
  font-size: 14px;
  font-weight: 700;
  color: #ffd43b;
  text-align: center;
}

.python-card-desc {
  font-size: 10px;
  color: var(--text-muted);
  text-align: center;
  margin-top: 4px;
  line-height: 1.4;
}

.python-chapter-body .lesson-nav-item.active {
  border-color: var(--python-blue);
  box-shadow: inset 2px 0 0 var(--python-blue), 0 0 8px rgba(48,105,152,0.1);
  color: var(--python-yellow) !important;
}

.python-chapter-body .lesson-nav-item.completed {
  color: rgba(255,255,255,0.4);
}

.python-chapter-body .lesson-nav-item.completed i {
  color: #22c55e !important;
}

.python-progress-badge {
  background: var(--python-blue-dim);
  border: 1px solid var(--python-blue-glow);
  color: var(--python-yellow);
  font-size: 10px;
  padding: 1px 5px;
  border-radius: 10px;
  font-weight: 600;
}

.sidebar-chapter-header.python-chapter-header.active-parent {
  border-left-color: var(--python-blue) !important;
}

@keyframes pulse-glow {
  0% {
    box-shadow: 0 0 8px rgba(0, 242, 254, 0.35);
  }
  50% {
    box-shadow: 0 0 18px rgba(0, 242, 254, 0.75), 0 0 28px rgba(0, 136, 255, 0.35);
  }
  100% {
    box-shadow: 0 0 8px rgba(0, 242, 254, 0.35);
  }
}

@keyframes pulse-glow-orange {
  0% {
    box-shadow: 0 0 8px rgba(99, 102, 241, 0.35);
  }
  50% {
    box-shadow: 0 0 18px rgba(99, 102, 241, 0.75), 0 0 28px rgba(129, 140, 248, 0.35);
  }
  100% {
    box-shadow: 0 0 8px rgba(99, 102, 241, 0.35);
  }
}

/* Textbook & Explanation Custom Styling Enhancements */
.textbook-section {
  font-family: 'Outfit', 'Noto Sans JP', sans-serif;
  line-height: 1.6;
}

.textbook-section h3 {
  font-size: 16px;
  color: var(--neon-cyan);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.concept-detail-box {
  background: rgba(10, 16, 32, 0.45) !important;
  border: 1px solid rgba(0, 242, 254, 0.15) !important;
  border-left: 4px solid var(--neon-cyan) !important;
  border-radius: 8px;
  padding: 14px 16px !important;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
  margin-bottom: 18px;
}

.concept-detail-box p {
  margin-bottom: 8px;
  font-size: 13.5px;
}

.concept-detail-box ul {
  padding-left: 20px;
  margin-top: 6px;
}

.concept-detail-box li {
  margin-bottom: 4px;
  font-size: 13px;
  color: var(--text-main);
}

/* Beautiful Walkthrough Table */
.code-walkthrough-panel {
  margin-top: 20px;
}

.code-walkthrough-panel h4 {
  font-size: 14.5px;
  color: var(--neon-cyan);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.walkthrough-table {
  width: 100%;
  border-collapse: separate !important;
  border-spacing: 0;
  margin-top: 8px;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.walkthrough-table th {
  background: rgba(22, 30, 46, 0.8) !important;
  color: var(--text-muted);
  font-weight: 600;
  padding: 10px 12px !important;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.walkthrough-table td {
  padding: 10px 12px !important;
  font-size: 12.5px;
  vertical-align: top;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  background: rgba(10, 16, 32, 0.2);
}

.walkthrough-table tr:last-child td {
  border-bottom: none;
}

.walkthrough-table tr:hover td {
  background: rgba(0, 242, 254, 0.02);
}

.walkthrough-table td:nth-child(2) {
  font-family: 'Fira Code', monospace !important;
  color: #00f2fe !important;
  background: rgba(0, 242, 254, 0.04) !important;
  font-weight: 500;
}

/* Gorgeous Pitfalls Card */
.textbook-pitfalls {
  margin-top: 20px;
  padding: 16px !important;
  border: 1px solid rgba(239, 68, 68, 0.25) !important;
  background: rgba(239, 68, 68, 0.04) !important;
  backdrop-filter: blur(8px);
  border-radius: 8px;
  box-shadow: 0 4px 15px rgba(239, 68, 68, 0.08);
  animation: border-pulse 4s infinite alternate ease-in-out;
}

@keyframes border-pulse {
  0% {
    border-color: rgba(239, 68, 68, 0.2);
    box-shadow: 0 4px 15px rgba(239, 68, 68, 0.05);
  }
  100% {
    border-color: rgba(239, 68, 68, 0.45);
    box-shadow: 0 4px 20px rgba(239, 68, 68, 0.15);
  }
}

.textbook-pitfalls h4 {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14.5px;
  font-weight: 700;
  margin-bottom: 10px;
}

.textbook-pitfalls p {
  font-size: 13px;
  line-height: 1.5;
  color: var(--text-main);
  margin-bottom: 8px;
}

.textbook-pitfalls p:last-child {
  margin-bottom: 0;
}


/* ==========================================================================
   CODING EXAM (模擬試験) — SQL / Java / Python
   ========================================================================== */

/* Sub-header tabs for SQL & Python (reuses .sub-header-tab base styles) */
#sql-sub-header .sub-header-tab.active {
  background: rgba(6, 182, 212, 0.1);
  border-color: rgba(6, 182, 212, 0.35);
  color: var(--neon-cyan);
}
#python-sub-header .sub-header-tab.active {
  background: var(--python-blue-dim);
  border-color: var(--python-blue-glow);
  color: var(--python-yellow);
}
#java-sub-header .sub-header-tab.active {
  background: var(--java-orange-dim);
  border-color: var(--java-orange);
  color: var(--java-orange);
}

/* ── Coding Exam Container ── */
.coding-exam-container {
  display: none;
  flex: 1;
  flex-direction: column;
  background: #070a13;
  width: 100%;
  height: 100%;
  overflow: hidden;
  animation: fadeIn 0.3s ease;
}
.coding-exam-container.visible {
  display: flex;
}

/* ── Config Screen ── */
.coding-exam-config-screen {
  display: flex;
  flex: 1;
  justify-content: center;
  align-items: center;
  padding: 40px;
  overflow-y: auto;
}
.coding-exam-config-card {
  width: 100%;
  max-width: 620px;
  background: rgba(15, 23, 42, 0.5);
  border: 1.5px solid rgba(255,255,255,0.1);
  border-radius: 16px;
  padding: 32px;
  box-shadow: 0 8px 40px rgba(0,0,0,0.5);
  backdrop-filter: blur(12px);
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.coding-exam-config-header {
  text-align: center;
}
.coding-exam-subject-icon {
  font-size: 40px;
  margin-bottom: 10px;
}
.coding-exam-config-header h2 {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 6px;
}
.coding-exam-config-header p {
  font-size: 12.5px;
  color: var(--text-muted);
  line-height: 1.6;
}
.coding-exam-options {
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.coding-exam-option-row {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.coding-exam-option-row label {
  font-size: 12.5px;
  font-weight: 500;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 6px;
}
.coding-exam-option-row select {
  background: #090d16;
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 8px 12px;
  border-radius: 8px;
  font-size: 13px;
  outline: none;
  cursor: pointer;
  transition: var(--transition-smooth);
}
.coding-exam-option-row select:focus {
  border-color: var(--neon-cyan);
  box-shadow: 0 0 8px var(--neon-cyan-glow);
}
.coding-exam-launch-btn {
  padding: 13px;
  border: none;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  color: #fff;
  background: linear-gradient(135deg, #0ea5e9, #6366f1);
  transition: var(--transition-smooth);
}
.coding-exam-launch-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 20px rgba(99,102,241,0.4);
}
.coding-exam-launch-btn.sql-theme { background: linear-gradient(135deg, #06b6d4, #0284c7); }
.coding-exam-launch-btn.java-theme { background: linear-gradient(135deg, var(--java-orange), hsl(25,90%,45%)); }
.coding-exam-launch-btn.python-theme { background: linear-gradient(135deg, #306998, #ffd43b); }

/* ── Testing Screen ── */
.coding-exam-testing-screen {
  display: none;
  flex-direction: column;
  flex: 1;
  overflow: hidden;
}
.coding-exam-testing-screen.visible {
  display: flex;
}
.coding-exam-top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 20px;
  background: rgba(0,0,0,0.35);
  border-bottom: 1px solid var(--border-color);
  min-height: 50px;
  flex-shrink: 0;
  gap: 12px;
}
.coding-exam-top-bar-left {
  display: flex;
  align-items: center;
  gap: 10px;
  flex: 1;
  min-width: 0;
}
.coding-exam-q-badge {
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 6px;
  padding: 3px 10px;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  white-space: nowrap;
}
.coding-exam-q-title-bar {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-main);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.coding-exam-timer {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  font-weight: 600;
  color: #fca5a5;
  background: rgba(239,68,68,0.1);
  border: 1px solid rgba(239,68,68,0.25);
  border-radius: 8px;
  padding: 4px 12px;
  white-space: nowrap;
}
.coding-exam-timer.ok {
  color: #86efac;
  background: rgba(34,197,94,0.08);
  border-color: rgba(34,197,94,0.2);
}
.coding-exam-top-bar-actions {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
}
.coding-exam-action-btn {
  background: rgba(255,255,255,0.05);
  border: 1px solid rgba(255,255,255,0.1);
  color: var(--text-muted);
  padding: 5px 14px;
  border-radius: 7px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}
.coding-exam-action-btn:hover {
  color: var(--text-main);
  background: rgba(255,255,255,0.08);
}
.coding-exam-action-btn.submit {
  background: linear-gradient(135deg, rgba(16,185,129,0.2), rgba(6,182,212,0.2));
  border-color: rgba(16,185,129,0.4);
  color: #6ee7b7;
}
.coding-exam-action-btn.submit:hover {
  background: linear-gradient(135deg, rgba(16,185,129,0.3), rgba(6,182,212,0.3));
  box-shadow: 0 0 12px rgba(16,185,129,0.2);
}
.coding-exam-action-btn.danger {
  border-color: rgba(239,68,68,0.3);
  color: #fca5a5;
}

/* ── Split body: task panel + sandbox panel ── */
.coding-exam-split-body {
  display: flex;
  flex: 1;
  overflow: hidden;
  gap: 0;
}

/* Left: task description */
.coding-exam-task-panel {
  width: 38%;
  min-width: 280px;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  border-right: 1px solid var(--border-color);
  overflow-y: auto;
  background: rgba(0,0,0,0.15);
  flex-shrink: 0;
}
.coding-exam-task-header {
  padding: 14px 18px 10px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.coding-exam-difficulty-badge {
  font-size: 11px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 4px;
  background: rgba(255,255,255,0.06);
  color: var(--text-muted);
  border: 1px solid rgba(255,255,255,0.1);
  letter-spacing: 0.5px;
}
.coding-exam-difficulty-badge.easy { background: rgba(16,185,129,0.12); color: #6ee7b7; border-color: rgba(16,185,129,0.3); }
.coding-exam-difficulty-badge.medium { background: rgba(245,158,11,0.12); color: #fcd34d; border-color: rgba(245,158,11,0.3); }
.coding-exam-difficulty-badge.hard { background: rgba(239,68,68,0.12); color: #fca5a5; border-color: rgba(239,68,68,0.3); }
.coding-exam-type-badge {
  font-size: 10px;
  font-weight: 600;
  padding: 2px 7px;
  border-radius: 4px;
  background: rgba(99,102,241,0.15);
  color: #a5b4fc;
  border: 1px solid rgba(99,102,241,0.3);
}
.coding-exam-task-body {
  padding: 16px 18px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  flex: 1;
}
.coding-exam-task-section-label {
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 5px;
}
.coding-exam-task-text {
  font-size: 13px;
  line-height: 1.75;
  color: var(--text-main);
}
.coding-exam-task-text-zh {
  font-size: 12px;
  line-height: 1.65;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  padding-top: 10px;
  margin-top: 4px;
}
.coding-exam-expected-block {
  background: rgba(0,0,0,0.3);
  border: 1px solid rgba(255,255,255,0.07);
  border-left: 3px solid var(--neon-cyan);
  border-radius: 6px;
  padding: 10px 14px;
  font-family: 'Fira Code', monospace;
  font-size: 12.5px;
  color: #86efac;
  white-space: pre-wrap;
  line-height: 1.6;
  max-height: 200px;
  overflow-y: auto;
}
.coding-exam-hint-block {
  background: rgba(245,158,11,0.05);
  border: 1px solid rgba(245,158,11,0.2);
  border-radius: 6px;
  padding: 10px 14px;
  font-size: 12px;
  color: #fcd34d;
  line-height: 1.6;
  display: none;
}
.coding-exam-hint-block.visible { display: block; }
.coding-exam-hint-toggle-btn {
  background: transparent;
  border: 1px dashed rgba(245,158,11,0.3);
  color: #fbbf24;
  padding: 4px 12px;
  border-radius: 6px;
  font-size: 11px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 5px;
  transition: var(--transition-smooth);
}
.coding-exam-hint-toggle-btn:hover {
  background: rgba(245,158,11,0.08);
}

/* Right: sandbox panel */
.coding-exam-sandbox-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}
.coding-exam-sandbox-header {
  padding: 8px 16px;
  background: rgba(0,0,0,0.2);
  border-bottom: 1px solid var(--border-color);
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}
.coding-exam-output-panel {
  display: flex;
  flex-direction: column;
  border-top: 1px solid var(--border-color);
  height: 200px;
  min-height: 120px;
  flex-shrink: 0;
  background: rgba(0,0,0,0.2);
}
.coding-exam-output-header {
  padding: 6px 14px;
  font-size: 11.5px;
  font-weight: 600;
  color: var(--text-muted);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
}
.coding-exam-output-content {
  flex: 1;
  overflow-y: auto;
  padding: 10px 14px;
  font-family: 'Fira Code', monospace;
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--text-main);
  white-space: pre-wrap;
}

/* ── Results Screen ── */
.coding-exam-results-screen {
  display: none;
  flex: 1;
  flex-direction: column;
  overflow: hidden;
}
.coding-exam-results-screen.visible {
  display: flex;
}
.coding-exam-results-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 24px;
  background: rgba(0,0,0,0.3);
  border-bottom: 1px solid var(--border-color);
  flex-shrink: 0;
}
.coding-exam-results-header h2 {
  font-size: 17px;
  font-weight: 700;
  color: var(--text-main);
  display: flex;
  align-items: center;
  gap: 10px;
}
.coding-exam-back-btn {
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 6px 16px;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
}
.coding-exam-back-btn:hover {
  color: var(--text-main);
  background: rgba(255,255,255,0.08);
}
.coding-exam-results-body {
  flex: 1;
  overflow-y: auto;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.coding-exam-score-banner {
  background: rgba(15,23,42,0.6);
  border: 1.5px solid var(--border-color);
  border-radius: 16px;
  padding: 24px;
  display: flex;
  align-items: center;
  gap: 24px;
  backdrop-filter: blur(8px);
}
.coding-exam-score-circle {
  width: 90px;
  height: 90px;
  border-radius: 50%;
  background: conic-gradient(var(--neon-cyan) 0% var(--score-pct, 0%), rgba(255,255,255,0.05) 0%);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  font-size: 22px;
  font-weight: 800;
  color: var(--text-main);
  box-shadow: 0 0 20px var(--neon-cyan-glow);
  position: relative;
}
.coding-exam-score-circle::before {
  content: '';
  position: absolute;
  inset: 8px;
  border-radius: 50%;
  background: #070a13;
}
.coding-exam-score-circle span {
  position: relative;
  z-index: 1;
}
.coding-exam-score-meta {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.coding-exam-score-meta h3 {
  font-size: 22px;
  font-weight: 800;
  color: var(--text-main);
}
.coding-exam-score-meta p {
  font-size: 13px;
  color: var(--text-muted);
}
.coding-exam-score-verdict {
  margin-top: 6px;
  padding: 4px 12px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  width: fit-content;
}
.coding-exam-score-verdict.pass {
  background: rgba(16,185,129,0.15);
  border: 1px solid rgba(16,185,129,0.35);
  color: #6ee7b7;
}
.coding-exam-score-verdict.fail {
  background: rgba(239,68,68,0.12);
  border: 1px solid rgba(239,68,68,0.3);
  color: #fca5a5;
}

/* Result list */
.coding-exam-result-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.coding-exam-result-item {
  background: rgba(15,23,42,0.5);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  overflow: hidden;
  transition: var(--transition-smooth);
}
.coding-exam-result-item.correct { border-color: rgba(16,185,129,0.3); }
.coding-exam-result-item.incorrect { border-color: rgba(239,68,68,0.25); }
.coding-exam-result-item-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  cursor: pointer;
  user-select: none;
}
.coding-exam-result-status-icon {
  font-size: 16px;
}
.coding-exam-result-status-icon.correct { color: #6ee7b7; }
.coding-exam-result-status-icon.incorrect { color: #fca5a5; }
.coding-exam-result-q-label {
  font-size: 11.5px;
  color: var(--text-muted);
  font-weight: 600;
  white-space: nowrap;
}
.coding-exam-result-q-title {
  font-size: 13px;
  color: var(--text-main);
  font-weight: 500;
  flex: 1;
}
.coding-exam-result-expand-body {
  display: none;
  padding: 12px 14px;
  border-top: 1px solid var(--border-color);
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.6;
  gap: 10px;
  flex-direction: column;
}
.coding-exam-result-expand-body.visible { display: flex; }
.coding-exam-result-code-block {
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  background: rgba(0,0,0,0.3);
  border-radius: 6px;
  padding: 8px 12px;
  white-space: pre-wrap;
  color: var(--text-main);
  max-height: 180px;
  overflow-y: auto;
}
.coding-exam-result-code-block.expected { color: #86efac; border-left: 3px solid rgba(16,185,129,0.4); }
.coding-exam-result-code-block.actual.wrong { color: #fca5a5; border-left: 3px solid rgba(239,68,68,0.4); }
.coding-exam-solution-block {
  font-family: 'Fira Code', monospace;
  font-size: 12px;
  background: rgba(99,102,241,0.06);
  border: 1px solid rgba(99,102,241,0.2);
  border-radius: 6px;
  padding: 8px 12px;
  white-space: pre-wrap;
  color: #c4b5fd;
  max-height: 200px;
  overflow-y: auto;
}

/* Nav between questions in exam */
.coding-exam-q-nav {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
}
.coding-exam-q-nav-btn {
  background: rgba(255,255,255,0.05);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  width: 30px;
  height: 30px;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  transition: var(--transition-smooth);
}
.coding-exam-q-nav-btn:hover {
  color: var(--text-main);
  background: rgba(255,255,255,0.08);
}
.coding-exam-q-nav-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

/* SQL exam uses the existing SQL editor — we just embed it inline */
.coding-exam-sql-editor-wrap {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.coding-exam-sql-editor-wrap .editor-container {
  flex: 1;
  min-height: 0;
  border-radius: 0;
  border: none;
}
.coding-exam-run-bar {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  padding: 8px 14px;
  border-top: 1px solid var(--border-color);
  gap: 8px;
  background: rgba(0,0,0,0.2);
  flex-shrink: 0;
}
.coding-exam-run-btn {
  background: linear-gradient(135deg, #06b6d4, #6366f1);
  border: none;
  color: #fff;
  padding: 7px 20px;
  border-radius: 8px;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 7px;
  transition: var(--transition-smooth);
}
.coding-exam-run-btn:hover {
  box-shadow: 0 0 14px rgba(99,102,241,0.4);
  transform: translateY(-1px);
}
.coding-exam-run-btn.java-theme {
  background: linear-gradient(135deg, var(--java-orange), hsl(25,90%,45%));
}
.coding-exam-run-btn.python-theme {
  background: linear-gradient(135deg, #306998, #00a8ff);
}

/* ==========================================================================
   UI REDESIGN & OPTIMIZATION OVERRIDES
   Minimalist Zinc Dark Theme, Cold Tone, Monochrome Grey
   ========================================================================== */

:root {
  --bg-primary: #09090b;
  --bg-secondary: #09090b;
  --bg-card: rgba(24, 24, 27, 0.7);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-color-glow: rgba(255, 255, 255, 0.15);
  
  --text-main: #f4f4f5;
  --text-muted: #a1a1aa;
  
  /* Reset bright neon colors to subtle greys and whites */
  --neon-cyan: #ffffff;
  --neon-cyan-glow: rgba(255, 255, 255, 0.03);
  --neon-blue: #e4e4e7;
  --neon-purple: #d4d4d8;
  --neon-purple-glow: rgba(255, 255, 255, 0.03);
  
  --success-color: #10b981;
  --success-glow: rgba(16, 185, 129, 0.1);
  --error-color: #ef4444;
  --error-glow: rgba(239, 68, 68, 0.1);
  
  --transition-smooth: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  --glass-blur: blur(16px);
}

/* Neutralize specific subject modes */
body.mode-java {
  --java-orange: #ffffff;
  --java-orange-dim: rgba(255, 255, 255, 0.04);
  --java-orange-glow: rgba(255, 255, 255, 0.02);
  --java-dark: #09090b;
  --java-editor-bg: #09090b;
  --java-editor-line: rgba(255, 255, 255, 0.03);
  --neon-cyan: #ffffff;
}

body.mode-python {
  --neon-cyan: #ffffff;
  --python-blue: #e4e4e7;
  --python-blue-dim: rgba(255, 255, 255, 0.04);
  --python-blue-glow: rgba(255, 255, 255, 0.02);
  --python-yellow: #ffffff;
  --python-yellow-dim: rgba(255, 255, 255, 0.04);
  --python-yellow-glow: rgba(255, 255, 255, 0.02);
  --python-editor-line: rgba(255, 255, 255, 0.03);
}

body.mode-sg {
  --neon-sg-teal: #ffffff;
  --neon-sg-teal-glow: rgba(255, 255, 255, 0.04);
  --neon-sg-teal-dim: rgba(255, 255, 255, 0.02);
  --neon-cyan: #ffffff;
}

.app-container, body.mode-sg {
  background-color: #09090b !important;
  background-image: 
    radial-gradient(circle at 50% 0%, rgba(255, 255, 255, 0.035) 0%, transparent 60%),
    linear-gradient(to bottom, #09090b, #09090b) !important;
  background-attachment: fixed !important;
}

/* Subject tab switcher buttons */
.subject-tab {
  border: 1px solid transparent !important;
  background: transparent !important;
  color: #a1a1aa !important;
  font-weight: 500 !important;
  border-radius: 6px !important;
  transition: var(--transition-smooth) !important;
  box-shadow: none !important;
}

.subject-tab:hover {
  color: #f4f4f5 !important;
  background: rgba(255, 255, 255, 0.04) !important;
}

/* Active subject tabs */
.subject-tab.active,
#subject-tab-itpass.active,
#subject-tab-java.active,
#subject-tab-python.active,
#subject-tab-sg.active {
  background: rgba(255, 255, 255, 0.08) !important;
  border: 1px solid rgba(255, 255, 255, 0.15) !important;
  color: #ffffff !important;
  box-shadow: 0 4px 12px rgba(255, 255, 255, 0.05) !important;
}

/* Sub-header tab buttons */
.sub-header-tab {
  background: transparent !important;
  border: 1px solid transparent !important;
  color: #a1a1aa !important;
  font-weight: 500 !important;
  border-radius: 6px !important;
  transition: var(--transition-smooth) !important;
}

.sub-header-tab:hover {
  color: #f4f4f5 !important;
  background: rgba(255, 255, 255, 0.03) !important;
}

/* Active sub-header tabs */
.sub-header-tab.active,
#sql-sub-header .sub-header-tab.active,
#python-sub-header .sub-header-tab.active,
#java-sub-header .sub-header-tab.active,
body.mode-sg .sub-header-tab.active {
  background: rgba(255, 255, 255, 0.08) !important;
  border: 1px solid rgba(255, 255, 255, 0.15) !important;
  color: #ffffff !important;
  box-shadow: 0 4px 12px rgba(255, 255, 255, 0.05) !important;
}

/* Sidebar lesson items */
.lesson-nav-item {
  color: #a1a1aa !important;
  border-left: 2px solid transparent !important;
  border-radius: 6px !important;
  background: transparent !important;
  transition: var(--transition-smooth) !important;
  padding: 8px 12px !important;
}

.lesson-nav-item:hover {
  background: rgba(255, 255, 255, 0.03) !important;
  color: #f4f4f5 !important;
}

.lesson-nav-item.active,
body.mode-sg .lesson-nav-item.active,
body.mode-java .lesson-nav-item.active,
body.mode-python .lesson-nav-item.active {
  background: rgba(255, 255, 255, 0.05) !important;
  color: #ffffff !important;
  border-left: 3px solid #ffffff !important;
  border-top-left-radius: 0 !important;
  border-bottom-left-radius: 0 !important;
  box-shadow: none !important;
  font-weight: 600 !important;
  text-shadow: none !important;
}

/* Sidebar progress bar */
.progress-bar-fill,
body.mode-sg .progress-bar-fill {
  background: #ffffff !important;
  box-shadow: 0 0 8px rgba(255, 255, 255, 0.5) !important;
}
.progress-info strong,
body.mode-sg .progress-info strong {
  color: #ffffff !important;
}

/* card stylings */
.content-card,
.playground-card,
.java-sandbox-card,
.python-sandbox-card,
.cbt-config-options {
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.4) !important;
  background: rgba(24, 24, 27, 0.6) !important;
}

/* Remove colored glows on focus for sandbox cards */
body.mode-python .python-sandbox-card:focus-within,
.java-sandbox-card:focus-within {
  border-color: rgba(255, 255, 255, 0.2) !important;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.5) !important;
}

/* Lesson titles & elements */
.lesson-badge,
.lesson-badge.java-badge,
.lesson-badge.python-badge,
body.mode-sg .lesson-badge {
  background: rgba(255, 255, 255, 0.06) !important;
  border: 1px solid rgba(255, 255, 255, 0.12) !important;
  color: #e4e4e7 !important;
  font-weight: 500 !important;
  text-transform: uppercase;
}

.vocab-highlight,
body.mode-sg .vocab-highlight {
  color: #ffffff !important;
  background: rgba(255, 255, 255, 0.06) !important;
  border-bottom: 1px dashed #a1a1aa !important;
}

/* Explanations columns */
.concept-col h4,
.concept-col.zh-col h4,
body.mode-sg .sidebar-title,
.itpass-widget .schema-header,
.itpass-widget .console-header,
.itpass-widget .output-header,
.java-sandbox-title {
  color: #e4e4e7 !important;
  font-weight: 600 !important;
}

.concept-body {
  background: rgba(9, 9, 11, 0.5) !important;
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
  color: #e4e4e7 !important;
}
.concept-body strong {
  color: #ffffff !important;
}
.concept-body code {
  background: rgba(255, 255, 255, 0.06) !important;
  color: #e4e4e7 !important;
  border: 1px solid rgba(255, 255, 255, 0.04) !important;
}

/* Analogy Card & Glossary Card */
.analogy-card {
  background: rgba(255, 255, 255, 0.02) !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
}
.analogy-card .card-icon {
  color: #e4e4e7 !important;
  filter: none !important;
}
.analogy-card .card-content h5 {
  color: #ffffff !important;
}

.example-card {
  background: #09090b !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
}
.example-header {
  background: rgba(255, 255, 255, 0.02) !important;
}
.example-card pre code {
  color: #f4f4f5 !important;
}

/* Primary Action Buttons */
.run-query-btn,
.quiz-submit-btn,
.cbt-launch-btn,
.coding-exam-run-btn,
.coding-exam-run-btn.java-theme,
.coding-exam-run-btn.python-theme {
  background: #ffffff !important;
  border: 1px solid rgba(255, 255, 255, 0.1) !important;
  color: #09090b !important;
  font-weight: 700 !important;
  box-shadow: 0 4px 12px rgba(255, 255, 255, 0.05) !important;
  animation: none !important;
}

.run-query-btn:hover,
.quiz-submit-btn:hover,
.cbt-launch-btn:hover,
.coding-exam-run-btn:hover {
  background: #e4e4e7 !important;
  transform: translateY(-1px) !important;
  box-shadow: 0 6px 16px rgba(255, 255, 255, 0.12) !important;
}

/* Secondary Action Buttons */
.copy-example-btn,
.header-challenge-btn-start,
.console-btn,
.reset-all-btn,
.java-vocab-flip-btn,
.python-vocab-flip-btn,
.java-vocab-nav-btn,
.python-vocab-nav-btn,
.quiz-nav-btn,
.cbt-nav-btn,
.cbt-results-close-btn,
.coding-exam-q-nav-btn {
  background: rgba(255, 255, 255, 0.04) !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
  color: #a1a1aa !important;
  transition: var(--transition-smooth) !important;
  box-shadow: none !important;
  height: auto !important;
  padding: 6px 12px !important;
}

.copy-example-btn:hover,
.header-challenge-btn-start:hover,
.console-btn:hover,
.reset-all-btn:hover,
.quiz-nav-btn:hover,
.cbt-nav-btn:hover,
.cbt-results-close-btn:hover,
.coding-exam-q-nav-btn:hover {
  background: rgba(255, 255, 255, 0.08) !important;
  border-color: rgba(255, 255, 255, 0.15) !important;
  color: #ffffff !important;
  transform: none !important;
  box-shadow: none !important;
}

/* Quiz questions & choices */
.quiz-question,
body.mode-sg .quiz-question {
  border-left: 3px solid #ffffff !important;
  background: rgba(255, 255, 255, 0.02) !important;
}

.quiz-option {
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
  background: transparent !important;
  transition: var(--transition-smooth) !important;
}
.quiz-option:hover {
  background: rgba(255, 255, 255, 0.02) !important;
  border-color: rgba(255, 255, 255, 0.12) !important;
}

.quiz-option.selected,
body.mode-sg .quiz-option.selected {
  border-color: #ffffff !important;
  background: rgba(255, 255, 255, 0.05) !important;
}
.quiz-option .option-marker {
  border: 2px solid #71717a !important;
  background: transparent !important;
  color: #a1a1aa !important;
}
.quiz-option.selected .option-marker,
body.mode-sg .quiz-option.selected .option-marker {
  border-color: #ffffff !important;
  background: #ffffff !important;
  color: #09090b !important;
}

/* Code Editors */
.editor-container {
  background: #09090b !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
  border-radius: 8px !important;
  overflow: hidden !important;
}
.line-numbers {
  background: rgba(255, 255, 255, 0.01) !important;
  border-right: 1px solid rgba(255, 255, 255, 0.06) !important;
  color: #52525b !important;
}
.sql-editor {
  color: #f4f4f5 !important;
  background: transparent !important;
}

/* Playgrounds headers */
.schema-header,
.console-header,
.output-header {
  background: rgba(255, 255, 255, 0.01) !important;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06) !important;
}

/* Output terminal */
.output-body {
  background: rgba(9, 9, 11, 0.4) !important;
}

.result-table th {
  background: rgba(255, 255, 255, 0.02) !important;
  color: #ffffff !important;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1) !important;
}
.result-table td {
  border-bottom: 1px solid rgba(255, 255, 255, 0.04) !important;
  color: #e4e4e7 !important;
}

.maximize-btn.active {
  color: #ffffff !important;
  border-color: #ffffff !important;
}
.output-card.maximized {
  background: #09090b !important;
  border: 1.5px solid rgba(255, 255, 255, 0.2) !important;
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.8) !important;
}

/* DB Schema structural visualizer tabs */
.db-group-tabs {
  background: rgba(0, 0, 0, 0.4) !important;
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
}
.db-group-tab.active {
  background: rgba(255, 255, 255, 0.08) !important;
  color: #ffffff !important;
}
.schema-tab.active {
  border-color: #ffffff !important;
  color: #ffffff !important;
  background: rgba(255, 255, 255, 0.06) !important;
}
.schema-table-details {
  background: rgba(0, 0, 0, 0.3) !important;
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
}
.schema-col-name {
  color: #e4e4e7 !important;
}
.schema-col-name.primary-key {
  color: #ffffff !important;
  font-weight: bold !important;
}
.schema-col-type {
  color: #a1a1aa !important;
}

/* Scrollbars */
::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.08) !important;
}
::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.2) !important;
}

/* CBT / Coding Exam config & panels */
.cbt-config-header-main h2,
#coding-exam-display-title,
.coding-indicator-badge,
.cbt-results-header h2 {
  color: #ffffff !important;
}

.cbt-config-options label {
  color: #e4e4e7 !important;
}

.eq-number {
  color: #ffffff !important;
}

.verify-status-badge {
  background: rgba(255, 255, 255, 0.05) !important;
  color: #a1a1aa !important;
}

.cbt-results-summary-row {
  background: rgba(255, 255, 255, 0.02) !important;
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
}

.coding-indicator-badge {
  background: rgba(255, 255, 255, 0.04) !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
}

/* Progress bar inside scorecards */
.field-score-fill,
#coding-results-progress-bar {
  background: #ffffff !important;
  box-shadow: 0 0 6px rgba(255, 255, 255, 0.4) !important;
}

/* Custom Calculator styles */
.tool-selector-group select,
#calculator-select,
#coding-exam-count {
  background: #09090b !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
  color: #f4f4f5 !important;
  border-radius: 6px !important;
}

/* Modern page load animation */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.concept-body,
.analogy-card,
.example-card,
.quiz-section,
.playground-card,
.cbt-config-card {
  animation: fadeInUp 0.4s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Remove bright pulse-glow animations */
@keyframes pulse-glow {
  0% { box-shadow: none; }
  50% { box-shadow: none; }
  100% { box-shadow: none; }
}
@keyframes pulse-glow-orange {
  0% { box-shadow: none; }
  50% { box-shadow: none; }
  100% { box-shadow: none; }
}

/* ==========================================================================
   LOGO ICON & SUBJECT TAB ICON VISIBILITY FIX
   ========================================================================== */

.logo-icon {
  background: none !important;
  -webkit-text-fill-color: initial !important;
  color: #ffffff !important;
  filter: drop-shadow(0 0 10px rgba(255, 255, 255, 0.5)) !important;
  opacity: 1 !important;
}

.subject-tab i {
  color: inherit !important;
  opacity: 0.9 !important;
}

.subject-tab.active i {
  color: #ffffff !important;
  filter: drop-shadow(0 0 6px rgba(255, 255, 255, 0.5)) !important;
}

/* ==========================================================================
   PURPLE DE-COLORING OVERRIDES (去除紫色元素)
   ========================================================================== */

.chapter-progress-badge,
.subsection-progress-badge,
.java-progress-badge,
.python-progress-badge {
  background: rgba(255, 255, 255, 0.05) !important;
  color: #e4e4e7 !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
}

.sidebar-chapter-header.expanded .chapter-arrow {
  color: #ffffff !important;
}

.sidebar-chapter-body .lesson-nav-item.active {
  background: rgba(255, 255, 255, 0.05) !important;
  border-color: rgba(255, 255, 255, 0.15) !important;
  color: #ffffff !important;
}

.quiz-question {
  border-left-color: #ffffff !important;
}

.quiz-option.selected {
  border-color: #ffffff !important;
  background: rgba(255, 255, 255, 0.05) !important;
}

.quiz-option.selected .option-marker {
  border-color: #ffffff !important;
  background: #ffffff !important;
  color: #09090b !important;
}

.concept-body .vocab-highlight,
.vocab-highlight {
  color: #ffffff !important;
  background: rgba(255, 255, 255, 0.06) !important;
  border-bottom: 1px dashed #a1a1aa !important;
}

.random-practice-btn.active-practice {
  background: rgba(255, 255, 255, 0.06) !important;
  border-color: rgba(255, 255, 255, 0.15) !important;
  color: #ffffff !important;
}

.itpass-widget .schema-header,
.itpass-widget .console-header,
.itpass-widget .output-header,
.flashcard-back h4,
.flashcard-counter,
.checklist-item i,
.cbt-results-header h2 {
  color: #ffffff !important;
}

.flashcard,
.flashcard-back,
.checklist-card,
.cbt-results-summary-row {
  border-color: rgba(255, 255, 255, 0.08) !important;
}

/* ==========================================================================
   UI HIERARCHY & DEPTH ENHANCEMENTS (可操作部分层次感优化)
   ========================================================================== */

/* Main Containers Depth */
.app-header {
  background: rgba(9, 9, 11, 0.8) !important;
  border-bottom: 1px solid rgba(255, 255, 255, 0.08) !important;
}

.sub-header-bar {
  background: #121214 !important;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06) !important;
}

.app-sidebar {
  background: #0d0d0f !important;
  border-right: 1px solid rgba(255, 255, 255, 0.08) !important;
}

/* Elevate interactive cards from app body */
.content-card,
.playground-card,
.java-sandbox-card,
.python-sandbox-card {
  background: #161618 !important; /* Slightly lighter surface for cards */
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5) !important;
}

/* Sinking effect for editors and output terminals to represent 'input/output fields' */
.editor-container,
.output-body,
.output-placeholder {
  background: #000000 !important; /* Pure black to sink input regions */
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
  box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.8) !important;
}

/* Active tab distinct elevation */
.subject-tab.active,
#subject-tab-itpass.active,
#subject-tab-java.active,
#subject-tab-python.active,
#subject-tab-sg.active {
  background: #27272a !important; /* Elevated grey tab background */
  border-color: rgba(255, 255, 255, 0.2) !important;
  color: #ffffff !important;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3) !important;
}

.sub-header-tab.active,
#sql-sub-header .sub-header-tab.active,
#python-sub-header .sub-header-tab.active,
#java-sub-header .sub-header-tab.active,
body.mode-sg .sub-header-tab.active {
  background: #27272a !important;
  border-color: rgba(255, 255, 255, 0.2) !important;
  color: #ffffff !important;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3) !important;
}

/* Inactive tabs hover depth */
.subject-tab:hover,
.sub-header-tab:hover {
  background: rgba(255, 255, 255, 0.04) !important;
  border-color: rgba(255, 255, 255, 0.08) !important;
}

/* Sidebar chapters hover & expansion states */
.sidebar-chapter-header {
  transition: var(--transition-smooth);
}
.sidebar-chapter-header:hover {
  background: rgba(255, 255, 255, 0.02);
}
.sidebar-chapter-header.active-parent {
  background: rgba(255, 255, 255, 0.01);
}

/* Interactive elements: buttons and options */
.run-query-btn,
.quiz-submit-btn,
.cbt-launch-btn,
.coding-exam-run-btn {
  background: #ffffff !important;
  border: 1px solid #ffffff !important;
  color: #000000 !important;
  box-shadow: 0 4px 12px rgba(255, 255, 255, 0.1) !important;
  transition: transform 0.2s cubic-bezier(0.16, 1, 0.3, 1), box-shadow 0.2s, background-color 0.2s !important;
}

.run-query-btn:hover,
.quiz-submit-btn:hover,
.cbt-launch-btn:hover,
.coding-exam-run-btn:hover {
  background: #f4f4f5 !important;
  transform: translateY(-2px) !important;
  box-shadow: 0 6px 20px rgba(255, 255, 255, 0.15) !important;
}

.run-query-btn:active,
.quiz-submit-btn:active,
.cbt-launch-btn:active {
  transform: translateY(0) !important;
  box-shadow: 0 2px 8px rgba(255, 255, 255, 0.05) !important;
}

/* Distinct depth for Quiz options */
.quiz-option {
  background: rgba(255, 255, 255, 0.01) !important;
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.15) !important;
  transition: var(--transition-smooth) !important;
}

.quiz-option:hover {
  background: rgba(255, 255, 255, 0.03) !important;
  border-color: rgba(255, 255, 255, 0.15) !important;
  transform: translateX(2px);
}

.quiz-option.selected {
  background: rgba(255, 255, 255, 0.05) !important;
  border-color: rgba(255, 255, 255, 0.3) !important;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3) !important;
}

/* Analogy card, glossaries - informative blocks */
.analogy-card,
.example-card {
  border: 1px solid rgba(255, 255, 255, 0.06) !important;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25) !important;
}

/* ==========================================================================
   FLASHCARD DE-COLORING OVERRIDES (去除右侧词卡紫色元素)
   ========================================================================== */

.flashcard-front {
  background: rgba(255, 255, 255, 0.02) !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
  color: #f4f4f5 !important;
}

.flashcard-front h3 {
  color: #ffffff !important;
}

.flashcard-front span {
  color: #a1a1aa !important;
}

.flashcard-back {
  background: rgba(255, 255, 255, 0.03) !important;
  border: 1px solid rgba(255, 255, 255, 0.12) !important;
  color: #ffffff !important;
}

.flashcard-back h4 {
  color: #ffffff !important;
}

.flashcard-back span {
  color: #a1a1aa !important;
}

/* ==========================================================================
   PDF FLOATING-MINIMIZED OVERRIDES (原书 PDF 最小化悬浮样式)
   ========================================================================== */

.pdf-viewer-panel.minimized {
  top: auto !important;
  left: auto !important;
  right: 24px !important;
  bottom: 24px !important;
  width: 320px !important;
  height: 52px !important;
  z-index: 9999 !important;
  border-radius: 12px !important;
  border: 1px solid rgba(255, 255, 255, 0.15) !important;
  box-shadow: 0 12px 36px rgba(0, 0, 0, 0.7) !important;
  animation: none !important;
}

.pdf-viewer-panel.minimized .pdf-iframe-container {
  display: none !important;
}

.pdf-viewer-panel.minimized .pdf-panel-header {
  border-bottom: none !important;
  padding: 12px 16px !important;
  background: #18181b !important;
}

.pdf-minimize-btn {
  background: rgba(255, 255, 255, 0.04) !important;
  border: 1px solid rgba(255, 255, 255, 0.08) !important;
  color: #a1a1aa !important;
  transition: var(--transition-smooth) !important;
}

.pdf-minimize-btn:hover {
  border-color: rgba(255, 255, 255, 0.25) !important;
  color: #ffffff !important;
}

/* ==========================================================================
   FULL SCREEN PDF VIEWER OVERRIDES (全屏 PDF 查看器覆盖)
   ========================================================================== */

.pdf-viewer-panel {
  position: fixed !important;
  top: 0 !important;
  left: 0 !important;
  right: 0 !important;
  bottom: 0 !important;
  width: 100vw !important;
  height: 100vh !important;
  z-index: 10000 !important;
  border-radius: 0 !important;
  border: none !important;
  margin: 0 !important;
  background: #09090b !important;
  box-shadow: none !important;
}

/* ==========================================================================
   ADVANCED INTERACTION & POLISH OVERRIDES (交互感与排版深度优化)
   ========================================================================== */

/* Overall app-wide transition definitions for spring-like animation */
.subject-tab,
.sub-header-tab,
.lesson-nav-item,
.sidebar-chapter-header,
.content-card,
.playground-card,
.java-sandbox-card,
.python-sandbox-card,
.run-query-btn,
.quiz-submit-btn,
.quiz-option {
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1) !important;
}

/* Card hover lift effect (提升卡片层次感与可交互感) */
.content-card:hover,
.playground-card:hover,
.java-sandbox-card:hover,
.python-sandbox-card:hover {
  transform: translateY(-4px) !important;
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.7) !important;
  border-color: rgba(255, 255, 255, 0.15) !important;
}

/* Sidebar list interaction updates */
.lesson-nav-item {
  position: relative !important;
  padding: 10px 14px !important;
  margin-bottom: 6px !important;
  overflow: hidden !important;
}

.lesson-nav-item::before {
  content: "" !important;
  position: absolute !important;
  left: 0 !important;
  top: 50% !important;
  transform: translateY(-50%) scaleX(0) !important;
  width: 3px !important;
  height: 60% !important;
  background: #ffffff !important;
  transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1) !important;
  transform-origin: left !important;
}

.lesson-nav-item:hover::before {
  transform: translateY(-50%) scaleX(1) !important;
}

.lesson-nav-item:hover {
  transform: translateX(4px) !important;
  background: rgba(255, 255, 255, 0.04) !important;
  color: #ffffff !important;
}

/* Chapter header interactions */
.sidebar-chapter-header {
  padding: 12px 16px !important;
  margin-top: 8px !important;
  border-radius: 8px !important;
}

.sidebar-chapter-header:hover {
  padding-left: 20px !important;
  background: rgba(255, 255, 255, 0.03) !important;
}

/* Flashcard 3D hover feedback */
.flashcard-outer {
  perspective: 1000px !important;
}

.flashcard {
  transform-style: preserve-3d !important;
  transition: transform 0.6s cubic-bezier(0.16, 1, 0.3, 1) !important;
}

/* Soft tilt effect on hover to indicate 3D card */
.flashcard-outer:hover .flashcard:not(.flipped) {
  transform: rotateY(12deg) rotateX(4deg) scale(1.02) !important;
}

.flashcard-outer:hover .flashcard.flipped {
  transform: rotateY(192deg) rotateX(-4deg) scale(1.02) !important;
}

/* Sub-header tab click feedback */
.sub-header-tab:active, .subject-tab:active {
  transform: scale(0.96) !important;
}

/* Input elements focus outlines and glows */
.editor-container {
  transition: border-color 0.3s, box-shadow 0.3s !important;
}

.editor-container:focus-within {
  border-color: rgba(255, 255, 255, 0.2) !important;
  box-shadow: 0 0 0 3px rgba(255, 255, 255, 0.05) !important;
}

/* Table rows interactions */
.result-table tr {
  transition: background-color 0.15s ease !important;
}

.result-table tr:hover {
  background: rgba(255, 255, 255, 0.04) !important;
  cursor: pointer !important;
}

/* ==========================================================================
   UX SOFTER ANIMATIONS & EDITOR CONTAINER HEIGHT FIX (动效柔和化与高度修复)
   ========================================================================== */

/* Reduce editor container minimum height to prevent pushing footer/execute button out of bounds */
.editor-container {
  min-height: 100px !important;
}

/* Softer system-wide transition curve and longer duration */
.subject-tab,
.sub-header-tab,
.lesson-nav-item,
.sidebar-chapter-header,
.content-card,
.playground-card,
.java-sandbox-card,
.python-sandbox-card,
.run-query-btn,
.quiz-submit-btn,
.quiz-option,
.flashcard,
.pdf-viewer-panel {
  transition: all 0.4s cubic-bezier(0.25, 0.8, 0.25, 1) !important;
}

/* Softer card hover lift */
.content-card:hover,
.playground-card:hover,
.java-sandbox-card:hover,
.python-sandbox-card:hover {
  transform: translateY(-2px) !important;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.6) !important;
  border-color: rgba(255, 255, 255, 0.12) !important;
}

/* Softer lesson navigation translation */
.lesson-nav-item:hover {
  transform: translateX(2px) !important;
  background: rgba(255, 255, 255, 0.04) !important;
}

/* Softer chapter header hover sliding */
.sidebar-chapter-header:hover {
  padding-left: 18px !important;
  background: rgba(255, 255, 255, 0.02) !important;
}

/* Softer 3D flashcard tilt */
.flashcard-outer:hover .flashcard:not(.flipped) {
  transform: rotateY(6deg) rotateX(2deg) scale(1.01) !important;
}

.flashcard-outer:hover .flashcard.flipped {
  transform: rotateY(186deg) rotateX(-2deg) scale(1.01) !important;
}

/* Softer quiz option slide */
.quiz-option:hover {
  background: rgba(255, 255, 255, 0.02) !important;
  border-color: rgba(255, 255, 255, 0.12) !important;
  transform: translateX(1px) !important;
}

/* ---- Theme Toggle Button ---- */
.theme-toggle-btn {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.12);
  color: var(--text-muted);
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 14px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition-smooth);
  height: 30px;
}

.theme-toggle-btn:hover {
  color: #fbbf24;
  border-color: rgba(251, 191, 36, 0.3);
  box-shadow: 0 0 8px rgba(251, 191, 36, 0.12);
}

/* ---- Language Switcher ---- */
.language-switcher {
  position: relative;
  flex: 0 0 auto;
  z-index: 1600;
}

.language-toggle-btn {
  height: 30px;
  min-width: 88px;
  padding: 6px 10px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-muted);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  font-size: 12px;
  font-weight: 650;
  transition: var(--transition-smooth);
}

.language-toggle-btn:hover,
.language-toggle-btn[aria-expanded="true"] {
  color: var(--neon-cyan);
  border-color: rgba(0, 242, 254, 0.35);
  box-shadow: 0 0 8px rgba(0, 242, 254, 0.12);
}

.language-toggle-btn strong {
  max-width: 64px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: inherit;
}

.language-popover {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: min(360px, calc(100vw - 24px));
  max-height: min(520px, calc(100vh - 92px));
  padding: 12px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background: rgba(12, 18, 30, 0.98);
  box-shadow: 0 18px 52px rgba(0, 0, 0, 0.38);
  backdrop-filter: var(--glass-blur);
  color: var(--text-main);
  opacity: 0;
  pointer-events: none;
  transform: translateY(-4px);
  transition: opacity 0.18s ease, transform 0.18s ease;
}

.language-popover.open {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.language-popover-head {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: 10px;
}

.language-popover-head strong {
  font-size: 14px;
}

.language-popover-head small {
  color: var(--text-muted);
  font-size: 11px;
  line-height: 1.45;
}

.language-search-wrap {
  height: 36px;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 0 10px;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-muted);
}

.language-search-wrap input {
  width: 100%;
  min-width: 0;
  border: 0;
  outline: 0;
  background: transparent;
  color: var(--text-main);
  font: inherit;
  font-size: 13px;
}

.language-options-list {
  margin-top: 10px;
  max-height: 390px;
  overflow: auto;
  display: grid;
  gap: 6px;
  padding-right: 2px;
}

.language-option {
  width: 100%;
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.025);
  color: var(--text-main);
  cursor: pointer;
  padding: 8px 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  text-align: left;
  transition: var(--transition-smooth);
}

.language-option:hover,
.language-option.active {
  border-color: rgba(0, 242, 254, 0.38);
  background: rgba(0, 242, 254, 0.08);
}

.language-option-main {
  font-size: 13px;
  font-weight: 700;
}

.language-option small {
  color: var(--text-muted);
  font-size: 11px;
  white-space: nowrap;
}

body.i18n-active {
  font-family: "Outfit", "Noto Sans JP", "Noto Sans Myanmar", "Noto Sans Thai", "Segoe UI", sans-serif;
}

body.i18n-active :where(.subject-tab, .sub-header-tab, .lesson-nav-item, .schema-tab, .output-header-tab, .db-group-tab, .language-toggle-btn, .quiz-submit-btn, .cbt-btn-action, .settings-btn) {
  white-space: normal;
  line-height: 1.15;
  overflow-wrap: anywhere;
}

body.i18n-active :where(.theme-toggle-btn, .ai-settings-btn, .console-btn, .ai-modal-close-btn) {
  white-space: nowrap;
}

body.i18n-active .concept-container {
  flex-direction: row;
}

body.i18n-active .concept-col.zh-col {
  direction: inherit;
  unicode-bidi: plaintext;
  flex: 1 1 100%;
  max-width: 100%;
}

body[data-i18n-dir="rtl"].i18n-active .concept-col.zh-col .concept-body,
body[data-i18n-dir="rtl"].i18n-active .concept-col.zh-col h4 {
  direction: rtl;
  text-align: right;
}

body[data-i18n-dir="rtl"].i18n-active .language-option-main {
  direction: rtl;
  unicode-bidi: plaintext;
}

.i18n-loading {
  color: var(--text-muted);
  font-style: italic;
}

/* ==========================================================================
   Typography ratio tuning
   ========================================================================== */

.app-header {
  gap: 14px;
  min-height: 64px;
}

.header-logo {
  flex: 0 0 260px;
  min-width: 220px;
}

.logo-text h1 {
  max-width: 180px;
  font-size: 18px;
  line-height: 1.18;
  letter-spacing: 0;
}

.logo-text span {
  font-size: 11.5px;
  line-height: 1.35;
}

.header-subject-selector {
  align-items: stretch;
  flex: 1 1 auto;
  min-width: 0;
  max-width: 1010px;
  overflow-x: auto;
  scrollbar-width: none;
}

.header-subject-selector::-webkit-scrollbar {
  display: none;
}

.subject-tab,
body.i18n-active .subject-tab {
  min-height: 38px;
  padding: 7px 14px !important;
  font-size: 13px !important;
  line-height: 1.2 !important;
  white-space: nowrap !important;
  overflow-wrap: normal !important;
  word-break: keep-all !important;
  justify-content: center;
  flex: 0 0 auto;
}

.subject-tab i {
  flex: 0 0 auto;
  font-size: 13px;
}

.sub-header-tab,
body.i18n-active .sub-header-tab {
  font-size: 13px !important;
  line-height: 1.25 !important;
  white-space: nowrap !important;
  overflow-wrap: normal !important;
  word-break: keep-all !important;
}

.sidebar-title {
  font-size: 15px;
  line-height: 1.35;
}

.progress-info {
  font-size: 13px;
  line-height: 1.3;
}

.sidebar-chapter-header {
  gap: 10px;
}

.chapter-header-title {
  min-width: 0;
  font-size: 15px;
  line-height: 1.35;
}

.chapter-progress-badge {
  flex: 0 0 auto;
  font-size: 12px !important;
  line-height: 1;
}

.lesson-nav-item,
body.i18n-active .lesson-nav-item {
  min-height: 44px;
  padding: 10px 12px !important;
  font-size: 14px !important;
  line-height: 1.42 !important;
  overflow-wrap: break-word !important;
  word-break: normal !important;
}

.lesson-nav-item span:first-child {
  min-width: 0;
}

.content-card {
  gap: 18px;
}

.lesson-header {
  padding-bottom: 14px;
}

.lesson-header-top {
  margin-bottom: 10px;
}

.lesson-badge {
  font-size: 12px !important;
  line-height: 1.15;
  letter-spacing: 0;
}

.lesson-header h2 {
  font-size: 24px;
  line-height: 1.28;
  font-weight: 700;
  letter-spacing: 0;
  margin-bottom: 6px;
}

.lesson-header h3 {
  font-size: 15px;
  line-height: 1.45;
  font-weight: 500;
}

.lang-tabs {
  width: 100%;
  max-width: 520px;
}

.lang-tab,
body.i18n-active .lang-tab {
  flex: 1 1 0;
  justify-content: center;
  min-height: 34px;
  padding: 7px 12px;
  font-size: 13px;
  line-height: 1.25;
  white-space: nowrap;
  overflow-wrap: normal;
  word-break: keep-all;
}

.concept-container {
  gap: 22px;
}

.concept-col h4 {
  font-size: 14px;
  line-height: 1.35;
  letter-spacing: 0;
  text-transform: none;
}

.concept-body {
  font-size: 15px;
  line-height: 1.78;
  padding: 18px 20px;
}

.concept-body code {
  font-size: 0.92em;
}

.analogy-card .card-content h5 {
  font-size: 14px;
  line-height: 1.35;
}

.analogy-card .card-content p {
  font-size: 14.5px;
  line-height: 1.7;
}

.schema-header,
.console-header,
.output-header {
  font-size: 14px;
  line-height: 1.35;
}

.playground-task-desc {
  font-size: 14px;
  line-height: 1.55;
}

.console-btn,
.db-group-tab,
.schema-tab,
.maximize-btn,
.reset-all-btn,
.header-challenge-btn-start,
.language-toggle-btn {
  line-height: 1.2 !important;
  white-space: nowrap !important;
  overflow-wrap: normal !important;
  word-break: keep-all !important;
}

@media (max-width: 1500px) {
  .header-logo {
    flex-basis: 220px;
  }

  .logo-text h1 {
    max-width: 160px;
    font-size: 16px;
  }

  .subject-tab,
  body.i18n-active .subject-tab {
    padding-inline: 11px !important;
    font-size: 12.5px !important;
  }
}

@media (max-width: 1180px) {
  .app-header {
    gap: 10px;
  }

  .header-logo {
    flex-basis: 190px;
    min-width: 180px;
  }

  .logo-text span {
    display: none;
  }
}

/* Global target-language mode: keep target text and Japanese readable without squeezing narrow columns. */
body.i18n-active .concept-container {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  align-items: stretch;
  gap: 18px;
}

body.i18n-active .concept-col {
  min-width: 0;
  width: 100%;
}

body.i18n-active .concept-col.zh-col,
body.i18n-active .concept-col.ja-col {
  flex: initial !important;
  max-width: none !important;
}

body.i18n-active .concept-col.zh-col {
  order: 1;
}

body.i18n-active .concept-col.ja-col {
  order: 2;
}

body.i18n-active .concept-body {
  overflow-wrap: break-word;
  word-break: normal;
}

body.i18n-active .concept-col.ja-col .concept-body {
  color: var(--text-secondary);
}

body.i18n-active .app-header {
  gap: 10px;
  padding-inline: 16px;
}

body.i18n-active .header-logo {
  flex: 0 0 180px;
  min-width: 160px;
}

body.i18n-active .logo-text span {
  display: none;
}

body.i18n-active .header-subject-selector {
  flex: 1 1 360px;
  max-width: none;
}

body.i18n-active .header-challenge {
  margin-right: 0;
}

body.i18n-active :where(
  .app-header,
  .subject-tab,
  .sub-header-tab,
  .sidebar-title,
  .sidebar-chapter-header,
  .lesson-nav-item,
  .schema-header,
  .console-header,
  .output-header,
  .schema-tab,
  .db-group-tab,
  .console-btn,
  .maximize-btn,
  .reset-all-btn,
  .header-challenge-btn-start,
  .language-toggle-btn,
  .language-option,
  .settings-btn
) {
  overflow-wrap: normal !important;
  word-break: keep-all !important;
}

body.i18n-active :where(
  .language-toggle-btn,
  .header-challenge-btn-start,
  .reset-all-btn,
  .console-btn,
  .db-group-tab,
  .schema-tab,
  .maximize-btn
) {
  min-width: 0;
}

body.i18n-active #language-current-label {
  min-width: 0;
  max-width: 96px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

body.i18n-active :where(
  .playground-task-desc,
  .analogy-card .card-content,
  .quiz-question,
  .quiz-feedback,
  .review-kaisetsu-text
) {
  white-space: pre-line;
}