/* ===================================================================
   CBT EXAM PORTAL - MODERN UNIVERSITY CBT STYLESHEET
   Supports Desktop, Tablet, Mobile, High Contrast, Dark/Light Mode
   =================================================================== */

:root {
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, Monaco, monospace;
  
  /* Light Theme (Default CBT Palette) */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --bg-accent: #e2e8f0;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --text-inverse: #ffffff;
  
  --border-light: #e2e8f0;
  --border-medium: #cbd5e1;
  --border-focus: #3b82f6;
  
  --primary-50: #eff6ff;
  --primary-100: #dbeafe;
  --primary-500: #3b82f6;
  --primary-600: #2563eb;
  --primary-700: #1d4ed8;
  
  --success-50: #f0fdf4;
  --success-100: #dcfce7;
  --success-500: #22c55e;
  --success-600: #16a34a;
  --success-700: #15803d;
  
  --warning-50: #fffbeb;
  --warning-100: #fef3c7;
  --warning-500: #f59e0b;
  --warning-600: #d97706;
  --warning-700: #b45309;
  
  --danger-50: #fef2f2;
  --danger-100: #fee2e2;
  --danger-500: #ef4444;
  --danger-600: #dc2626;
  --danger-700: #b91c1c;

  --purple-500: #8b5cf6;
  --purple-600: #7c3aed;

  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-full: 9999px;

  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #090d16;
  --bg-secondary: #111827;
  --bg-tertiary: #1f2937;
  --bg-accent: #374151;
  
  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  --text-inverse: #0f172a;
  
  --border-light: #1f2937;
  --border-medium: #374151;
  
  --primary-50: rgba(59, 130, 246, 0.16);
  --primary-100: rgba(59, 130, 246, 0.28);
  --primary-500: #3b82f6;
  --primary-600: #60a5fa;
  --primary-700: #93c5fd;

  --success-50: rgba(16, 185, 129, 0.18);
  --success-100: rgba(16, 185, 129, 0.3);
  --success-500: #10b981;
  --success-600: #34d399;
  --success-700: #6ee7b7;

  --warning-50: rgba(245, 158, 11, 0.18);
  --warning-100: rgba(245, 158, 11, 0.3);
  --warning-500: #f59e0b;
  --warning-600: #fbbf24;
  --warning-700: #fde68a;

  --danger-50: rgba(239, 68, 68, 0.18);
  --danger-100: rgba(239, 68, 68, 0.3);
  --danger-500: #ef4444;
  --danger-600: #f87171;
  --danger-700: #fca5a5;

  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.5);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.6);
}

/* Base Reset */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header & Top Navigation */
.app-header {
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border-light);
  position: sticky;
  top: 0;
  z-index: 50;
  box-shadow: var(--shadow-sm);
}

.header-container {
  max-width: 1440px;
  margin: 0 auto;
  padding: 0.75rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-section {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.brand-logo {
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, var(--primary-600), var(--purple-600));
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 800;
  font-size: 1.25rem;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
}

.brand-info h1 {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.brand-info p {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

.exam-meta-pill {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  background: var(--bg-tertiary);
  padding: 0.4rem 1rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-light);
}

.meta-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.825rem;
  color: var(--text-secondary);
}

.meta-item strong {
  color: var(--text-primary);
}

/* Timer Display */
.timer-container {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--bg-primary);
  border: 2px solid var(--border-medium);
  padding: 0.35rem 0.9rem;
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  transition: var(--transition);
}

.timer-container.timer-warning {
  border-color: var(--warning-500);
  background-color: var(--warning-50);
  color: var(--warning-700);
}

.timer-container.timer-urgent {
  border-color: var(--danger-500);
  background-color: var(--danger-50);
  color: var(--danger-600);
  animation: pulse-border 1.2s infinite;
}

@keyframes pulse-border {
  0%, 100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(239, 68, 68, 0.4); }
  50% { transform: scale(1.02); box-shadow: 0 0 0 6px rgba(239, 68, 68, 0.15); }
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

/* Button styles */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: var(--font-sans);
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.55rem 1.15rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}

.btn-primary {
  background-color: var(--primary-600);
  color: #fff;
}
.btn-primary:hover {
  background-color: var(--primary-700);
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  border-color: var(--border-medium);
}
.btn-secondary:hover {
  background-color: var(--bg-accent);
}

.btn-danger {
  background-color: var(--danger-600);
  color: #fff;
}
.btn-danger:hover {
  background-color: var(--danger-700);
}

.btn-warning {
  background-color: var(--warning-500);
  color: #fff;
}
.btn-warning:hover {
  background-color: var(--warning-600);
}

.btn-icon {
  width: 38px;
  height: 38px;
  padding: 0;
  border-radius: var(--radius-md);
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border: 1px solid var(--border-light);
}
.btn-icon:hover {
  background: var(--bg-accent);
  color: var(--text-primary);
}

/* Layout Container */
.main-wrapper {
  flex: 1;
  max-width: 1440px;
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem;
}

/* SCREEN 1: Setup & Welcome */
.setup-view {
  max-width: 900px;
  margin: 1.5rem auto;
}

.hero-card {
  background: var(--bg-secondary);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
  padding: 2.25rem;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}

.hero-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 5px;
  background: linear-gradient(90deg, var(--primary-600), var(--purple-600));
}

.hero-title-group h2 {
  font-size: 1.85rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.hero-title-group p {
  color: var(--text-secondary);
  font-size: 1rem;
}

.config-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
  margin: 2rem 0;
}

.config-field {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.config-field label {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
}

.config-select, .config-input {
  width: 100%;
  padding: 0.7rem 1rem;
  font-size: 0.95rem;
  font-family: var(--font-sans);
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  border: 1.5px solid var(--border-medium);
  border-radius: var(--radius-md);
  outline: none;
  transition: var(--transition);
}

.config-select:focus, .config-input:focus {
  border-color: var(--primary-500);
  background-color: var(--bg-secondary);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

.mode-cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin-top: 0.5rem;
}

.mode-card {
  border: 2px solid var(--border-light);
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 1.2rem;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.mode-card:hover {
  border-color: var(--primary-500);
  background: var(--bg-secondary);
}

.mode-card.selected {
  border-color: var(--primary-600);
  background: var(--primary-50);
}

.mode-card h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.mode-card p {
  font-size: 0.825rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

.instructions-box {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin-bottom: 2rem;
}

.instructions-box h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.instructions-list {
  padding-left: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.shortcut-badge {
  background: var(--bg-secondary);
  border: 1px solid var(--border-medium);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  color: var(--text-primary);
  font-weight: 700;
}

/* SCREEN 2: Active CBT Exam Layout */
.exam-layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 1.5rem;
  align-items: start;
}

.exam-main {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.question-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-md);
  position: relative;
}

.question-meta-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-light);
}

.q-badge-group {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.badge {
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.25rem 0.65rem;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.badge-qnum {
  background: var(--primary-100);
  color: var(--primary-700);
}

.badge-topic {
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border: 1px solid var(--border-medium);
}

.badge-difficulty {
  background: #fef3c7;
  color: #92400e;
}

.badge-difficulty.hard {
  background: #fee2e2;
  color: #991b1b;
}

.question-text {
  font-size: 1.15rem;
  line-height: 1.65;
  color: var(--text-primary);
  font-weight: 500;
  margin-bottom: 2rem;
}

/* Math formatting in questions */
.katex-display {
  margin: 0.85em 0 !important;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 0.3em 0;
}

/* Options Container */
.options-grid {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.option-card {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  background: var(--bg-tertiary);
  border: 2px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 1rem 1.25rem;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
}

.option-card:hover {
  border-color: var(--border-medium);
  background: var(--bg-secondary);
  transform: translateX(3px);
}

.option-card.selected {
  border-color: var(--primary-600);
  background: var(--primary-50);
}

.option-indicator {
  width: 32px;
  height: 32px;
  min-width: 32px;
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  border: 1.5px solid var(--border-medium);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--text-secondary);
  transition: var(--transition);
}

.option-card.selected .option-indicator {
  background: var(--primary-600);
  border-color: var(--primary-600);
  color: #fff;
}

.option-content {
  flex: 1;
  font-size: 1rem;
  line-height: 1.5;
  color: var(--text-primary);
  padding-top: 0.2rem;
}

/* Practice Mode Instant Explanation Box */
.instant-feedback-card {
  margin-top: 1.5rem;
  border-radius: var(--radius-md);
  padding: 1.25rem;
  border: 1.5px solid var(--border-medium);
  background: var(--bg-tertiary);
  animation: fadeIn 0.3s ease-in-out;
}

.instant-feedback-card.correct {
  border-color: var(--success-500);
  background: var(--success-50);
}

.instant-feedback-card.incorrect {
  border-color: var(--danger-500);
  background: var(--danger-50);
}

.instant-feedback-title {
  font-size: 0.95rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.instant-feedback-card.correct .instant-feedback-title {
  color: var(--success-700);
}

.instant-feedback-card.incorrect .instant-feedback-title {
  color: var(--danger-700);
}

.instant-feedback-body {
  font-size: 0.9rem;
  color: var(--text-primary);
  line-height: 1.55;
}

/* Question Action Footer */
.question-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 1rem 1.5rem;
  box-shadow: var(--shadow-sm);
  flex-wrap: wrap;
}

.footer-nav-group, .footer-status-group {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Flagged state */
.btn-flag.is-flagged {
  background-color: var(--warning-100);
  color: var(--warning-700);
  border-color: var(--warning-500);
}

/* Sidebar Navigator Palette */
.palette-sidebar {
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  box-shadow: var(--shadow-md);
  position: sticky;
  top: 5rem;
}

.palette-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
}

.palette-header h3 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
}

.palette-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.palette-stat-item {
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  padding: 0.6rem 0.4rem;
  text-align: center;
  border: 1px solid var(--border-light);
}

.stat-value {
  font-size: 1.2rem;
  font-weight: 800;
  font-family: var(--font-mono);
  display: block;
}

.stat-label {
  font-size: 0.68rem;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 600;
}

.stat-answered .stat-value { color: var(--success-600); }
.stat-flagged .stat-value { color: var(--warning-600); }
.stat-unanswered .stat-value { color: var(--text-muted); }

/* Filter Tabs */
.palette-filters {
  display: flex;
  gap: 0.35rem;
  background: var(--bg-tertiary);
  padding: 0.25rem;
  border-radius: var(--radius-md);
  margin-bottom: 1rem;
}

.filter-btn {
  flex: 1;
  background: transparent;
  border: none;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.35rem;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition);
}

.filter-btn.active {
  background: var(--bg-secondary);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
}

/* Palette Grid */
.palette-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(42px, 1fr));
  gap: 0.45rem;
  max-height: 360px;
  overflow-y: auto;
  padding: 0.25rem;
  margin-bottom: 1.5rem;
}

.palette-cell {
  height: 40px;
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  border: 1.5px solid var(--border-medium);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  transition: var(--transition);
}

.palette-cell:hover {
  transform: scale(1.08);
  border-color: var(--primary-500);
}

/* Answered Cell */
.palette-cell.answered {
  background: var(--success-500);
  border-color: var(--success-600);
  color: #fff;
}

/* Flagged Cell */
.palette-cell.flagged {
  background: var(--warning-500);
  border-color: var(--warning-600);
  color: #fff;
}

.palette-cell.flagged::after {
  content: '★';
  position: absolute;
  top: 1px;
  right: 2px;
  font-size: 0.55rem;
  color: #fff;
}

/* Both Answered & Flagged */
.palette-cell.answered.flagged {
  background: linear-gradient(135deg, var(--success-500) 50%, var(--warning-500) 50%);
  color: #fff;
}

/* Current Active Cell */
.palette-cell.current {
  box-shadow: 0 0 0 3px var(--primary-500);
  border-color: #fff;
}

/* SCREEN 3: Results & Diagnostic Analytics */
.results-view {
  max-width: 1080px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.score-hero-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
  position: relative;
  overflow: hidden;
}

.score-hero-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 6px;
  background: linear-gradient(90deg, var(--success-500), var(--primary-500), var(--purple-500));
}

.score-primary-info h2 {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.score-primary-info p {
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.grade-badge-display {
  display: inline-block;
  margin-top: 0.75rem;
  padding: 0.35rem 1rem;
  border-radius: var(--radius-full);
  font-size: 0.9rem;
  font-weight: 800;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

.grade-badge-display.grade-a {
  background: var(--success-100);
  color: var(--success-700);
  border: 1px solid var(--success-500);
}

.grade-badge-display.grade-b, .grade-badge-display.grade-c {
  background: var(--primary-100);
  color: var(--primary-700);
  border: 1px solid var(--primary-500);
}

.grade-badge-display.grade-fail {
  background: var(--danger-100);
  color: var(--danger-700);
  border: 1px solid var(--danger-500);
}

.score-gauge-box {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.score-circle {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  background: conic-gradient(var(--primary-600) calc(var(--score-pct, 0) * 1%), var(--bg-tertiary) 0);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  position: relative;
}

.score-circle-inner {
  width: 110px;
  height: 110px;
  border-radius: 50%;
  background: var(--bg-secondary);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.score-circle-inner .pct {
  font-size: 1.75rem;
  font-weight: 800;
  font-family: var(--font-mono);
  color: var(--text-primary);
  line-height: 1;
}

.score-circle-inner .sub {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 600;
}

.score-quick-stats {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.quick-stat-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  font-size: 0.95rem;
}

.quick-stat-row span {
  color: var(--text-muted);
}

.quick-stat-row strong {
  font-family: var(--font-mono);
  color: var(--text-primary);
}

/* Topic Breakdown Card */
.topic-analytics-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-md);
}

.topic-analytics-card h3 {
  font-size: 1.25rem;
  font-weight: 800;
  margin-bottom: 1.25rem;
}

.topic-bar-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.topic-bar-item {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.topic-bar-header {
  display: flex;
  justify-content: space-between;
  font-size: 0.875rem;
  font-weight: 600;
}

.topic-progress-track {
  width: 100%;
  height: 10px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.topic-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary-600), var(--purple-600));
  border-radius: var(--radius-full);
  transition: width 0.8s ease-out;
}

/* Review Section */
.review-section {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.review-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.review-header h3 {
  font-size: 1.35rem;
  font-weight: 800;
}

.review-filter-tabs {
  display: flex;
  gap: 0.5rem;
}

.review-question-card {
  background: var(--bg-secondary);
  border: 1.5px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.review-question-card.status-correct {
  border-left: 5px solid var(--success-500);
}

.review-question-card.status-incorrect {
  border-left: 5px solid var(--danger-500);
}

.review-question-card.status-skipped {
  border-left: 5px solid var(--text-muted);
}

.review-options-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.review-option {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--border-light);
  display: flex;
  align-items: center;
  gap: 0.85rem;
  font-size: 0.95rem;
  color: var(--text-primary);
  background: var(--bg-secondary);
  transition: var(--transition);
}

.review-option .option-text {
  color: var(--text-primary);
}

.review-option.is-correct-target {
  background: var(--success-50);
  border-color: var(--success-500);
  color: var(--text-primary);
  font-weight: 600;
}

.review-option.is-user-wrong {
  background: var(--danger-50);
  border-color: var(--danger-500);
  color: var(--text-primary);
}

[data-theme="dark"] .review-option.is-correct-target {
  background: rgba(16, 185, 129, 0.16);
  border-color: #10b981;
  color: #f9fafb;
}

[data-theme="dark"] .review-option.is-user-wrong {
  background: rgba(239, 68, 68, 0.16);
  border-color: #ef4444;
  color: #f9fafb;
}

[data-theme="dark"] .review-option.is-correct-target strong {
  color: #34d399 !important;
}

[data-theme="dark"] .review-option.is-user-wrong strong {
  color: #f87171 !important;
}

.solution-box {
  background: var(--bg-tertiary);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: 1.2rem;
  margin-top: 0.5rem;
}

.solution-box h5 {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--primary-600);
  margin-bottom: 0.4rem;
}

.solution-box p {
  font-size: 0.9rem;
  color: var(--text-primary);
  line-height: 1.6;
}

/* Modals */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  animation: fadeIn 0.2s ease-out;
}

.modal-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-lg);
  max-width: 520px;
  width: 100%;
  padding: 2rem;
  box-shadow: var(--shadow-xl);
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.modal-header h3 {
  font-size: 1.25rem;
  font-weight: 800;
}

.modal-summary-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.75rem;
  background: var(--bg-tertiary);
  padding: 1rem;
  border-radius: var(--radius-md);
  text-align: center;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

/* Scientific Calculator Modal */
.calc-modal {
  max-width: 360px;
  padding: 1.25rem;
  border-radius: var(--radius-lg);
}

.calc-screen {
  background: #0f172a;
  color: #38bdf8;
  font-family: var(--font-mono);
  font-size: 1.5rem;
  text-align: right;
  padding: 1rem;
  border-radius: var(--radius-md);
  margin-bottom: 1rem;
  word-break: break-all;
  min-height: 60px;
  display: flex;
  align-items: center;
  justify-content: flex-end;
}

.calc-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.5rem;
}

.calc-btn {
  padding: 0.75rem 0.5rem;
  font-size: 1rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-medium);
  background: var(--bg-tertiary);
  color: var(--text-primary);
  cursor: pointer;
  transition: var(--transition);
}

.calc-btn:hover {
  background: var(--bg-accent);
}

.calc-btn.op {
  background: var(--primary-100);
  color: var(--primary-700);
  border-color: var(--primary-500);
}

.calc-btn.action {
  background: var(--danger-100);
  color: var(--danger-700);
  border-color: var(--danger-500);
}

/* Animation utilities */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ===================================================================
   FREEMIUM TEASER & FULL UNLOCK PAYWALL STYLES
   =================================================================== */

.btn-unlock-pill {
  background: linear-gradient(135deg, #f59e0b, #d97706);
  color: #ffffff;
  font-weight: 700;
  font-size: 0.82rem;
  padding: 0.45rem 0.9rem;
  border-radius: var(--radius-full);
  border: none;
  box-shadow: 0 2px 8px rgba(245, 158, 11, 0.35);
  cursor: pointer;
  transition: var(--transition);
}

.btn-unlock-pill:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(245, 158, 11, 0.5);
}

.badge-pro-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  background: var(--success-100);
  color: var(--success-700);
  border: 1px solid var(--success-500);
  font-weight: 700;
  font-size: 0.8rem;
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-full);
  cursor: pointer;
}

.btn-gold {
  background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  color: #ffffff;
  font-weight: 800;
  border: none;
  box-shadow: 0 4px 14px rgba(217, 119, 6, 0.35);
}

.btn-gold:hover {
  background: linear-gradient(135deg, #fbbf24 0%, #b45309 100%);
  transform: translateY(-1px);
}

.freemium-banner {
  background: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
  color: #f8fafc;
  border: 1.5px solid #f59e0b;
  border-radius: var(--radius-lg);
  padding: 1.5rem 2rem;
  margin-bottom: 1.75rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  flex-wrap: wrap;
  box-shadow: var(--shadow-lg);
}

.freemium-banner-left {
  flex: 1;
  min-width: 260px;
}

.freemium-tag {
  display: inline-block;
  background: rgba(245, 158, 11, 0.2);
  color: #fbbf24;
  border: 1px solid #f59e0b;
  font-size: 0.72rem;
  font-weight: 800;
  padding: 0.2rem 0.65rem;
  border-radius: var(--radius-full);
  letter-spacing: 0.06em;
  margin-bottom: 0.5rem;
}

.freemium-banner-left h3 {
  font-size: 1.25rem;
  font-weight: 800;
  margin-bottom: 0.35rem;
  color: #ffffff;
}

.freemium-banner-left p {
  font-size: 0.92rem;
  color: #cbd5e1;
  line-height: 1.5;
}

.inline-lock-tag {
  display: inline-block;
  background: var(--warning-100);
  color: var(--warning-700);
  border: 1px solid var(--warning-500);
  font-size: 0.68rem;
  font-weight: 800;
  padding: 0.1rem 0.45rem;
  border-radius: var(--radius-full);
  margin-left: 0.35rem;
  vertical-align: middle;
}

.mode-card.locked-card {
  position: relative;
  opacity: 0.85;
  border-style: dashed;
}

.mode-card.locked-card:hover {
  border-color: var(--warning-500);
}

/* Upsell Card on Results Screen */
.freemium-upsell-card {
  background: linear-gradient(135deg, #0f172a 0%, #1e1b4b 100%);
  color: #ffffff;
  border: 2px solid #f59e0b;
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-xl);
}

.upsell-badge {
  display: inline-block;
  background: rgba(245, 158, 11, 0.2);
  color: #fbbf24;
  border: 1px solid #f59e0b;
  font-size: 0.72rem;
  font-weight: 800;
  padding: 0.2rem 0.65rem;
  border-radius: var(--radius-full);
  letter-spacing: 0.06em;
}

.upsell-header h3 {
  font-size: 1.45rem;
  font-weight: 800;
  margin: 0.5rem 0 0.4rem;
}

.upsell-header p {
  color: #cbd5e1;
  font-size: 0.95rem;
  max-width: 760px;
}

.upsell-perks-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 0.75rem;
  margin-top: 1.25rem;
  background: rgba(255, 255, 255, 0.06);
  padding: 1rem 1.25rem;
  border-radius: var(--radius-md);
}

.upsell-perk {
  font-size: 0.9rem;
  color: #f1f5f9;
}

/* Locked Solution Box in Free Review */
.solution-locked-box {
  position: relative;
  background: var(--bg-tertiary);
  border: 1.5px dashed var(--warning-500);
  border-radius: var(--radius-md);
  padding: 1.35rem;
  margin-top: 0.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.solution-locked-info h5 {
  font-size: 0.9rem;
  font-weight: 800;
  color: var(--warning-700);
  margin-bottom: 0.25rem;
}

[data-theme="dark"] .solution-locked-info h5 {
  color: #fbbf24;
}

.solution-locked-info p {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* Unlock Modal */
.unlock-modal-card {
  max-width: 540px;
  gap: 1.15rem;
}

.unlock-modal-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.unlock-modal-header h3 {
  font-size: 1.35rem;
  font-weight: 800;
}

.unlock-reason-banner {
  background: var(--warning-100);
  color: var(--warning-700);
  border-left: 4px solid var(--warning-500);
  padding: 0.65rem 0.9rem;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  font-weight: 600;
}

.unlock-price-box {
  background: linear-gradient(135deg, #1e293b, #0f172a);
  color: #ffffff;
  padding: 1rem 1.25rem;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  border: 1px solid #334155;
}

.price-left {
  display: flex;
  flex-direction: column;
}

.price-label {
  font-weight: 800;
  font-size: 0.95rem;
  color: #f8fafc;
}

.price-sub {
  font-size: 0.78rem;
  color: #94a3b8;
}

.price-amount {
  font-family: var(--font-mono);
  font-size: 1.65rem;
  font-weight: 800;
  color: #fbbf24;
}

.payment-steps-box, .code-redemption-box {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.payment-steps-box h4, .code-redemption-box h4 {
  font-size: 0.9rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-secondary);
}

.bank-details-card {
  background: var(--bg-tertiary);
  border: 1.5px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: 0.95rem 1.15rem;
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.bank-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.92rem;
}

.bank-row span {
  color: var(--text-muted);
  font-weight: 500;
}

.mono-acct {
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: var(--primary-600);
  letter-spacing: 0.05em;
}

.btn-copy-mini {
  background: var(--primary-100);
  color: var(--primary-700);
  border: 1px solid var(--primary-500);
  border-radius: var(--radius-sm);
  padding: 0.15rem 0.55rem;
  font-size: 0.75rem;
  font-weight: 700;
  cursor: pointer;
}

.btn-copy-mini:hover {
  background: var(--primary-600);
  color: #ffffff;
}

.btn-whatsapp {
  background: #16a34a;
  color: #ffffff;
  text-decoration: none;
  text-align: center;
  font-weight: 700;
  font-size: 0.9rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  transition: var(--transition);
}

.btn-whatsapp:hover {
  background: #15803d;
}

.code-input-group {
  display: flex;
  gap: 0.5rem;
}

.code-input {
  flex: 1;
  padding: 0.75rem 1rem;
  border: 1.5px solid var(--border-medium);
  border-radius: var(--radius-md);
  background: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.code-input:focus {
  outline: none;
  border-color: var(--primary-500);
}

.unlock-feedback-msg {
  font-size: 0.85rem;
  font-weight: 600;
  padding: 0.55rem 0.8rem;
  border-radius: var(--radius-sm);
}

.unlock-feedback-msg.error {
  background: var(--danger-100);
  color: var(--danger-700);
}

.unlock-feedback-msg.success {
  background: var(--success-100);
  color: var(--success-700);
}

/* ===================================================================
   MULTI-COURSE DEPARTMENT CATALOG GRID
   =================================================================== */

.course-catalog-section {
  margin-bottom: 1.75rem;
}

.course-catalog-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.course-catalog-header label {
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

.course-count-badge {
  font-size: 0.78rem;
  font-weight: 700;
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-full);
  background: var(--primary-100);
  color: var(--primary-700);
}

.course-cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 0.85rem;
}

.course-card-item {
  border: 2px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 1rem 1.15rem;
  background: var(--bg-primary);
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  position: relative;
}

.course-card-item:hover {
  border-color: var(--primary-500);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.course-card-item.active {
  border-color: var(--primary-600);
  background: var(--primary-50);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.12);
}

.course-card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
}

.course-code-pill {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 800;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
  background: var(--primary-600);
  color: #ffffff;
}

.course-qcount-tag {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-muted);
}

.course-card-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.course-card-desc {
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

/* Student Identity Inputs & Anti-Screenshot Watermark */
.student-id-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

@media (max-width: 560px) {
  .student-id-grid {
    grid-template-columns: 1fr;
  }
}

.student-input {
  font-family: var(--font-sans);
  font-size: 0.88rem;
  font-weight: 600;
  text-transform: none;
  letter-spacing: normal;
  padding: 0.65rem 0.85rem;
}

.exam-watermark {
  position: absolute;
  inset: 0;
  pointer-events: none;
  user-select: none;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  z-index: 1;
  opacity: 0.045;
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 800;
  text-align: center;
  line-height: 2.4;
  transform: rotate(-18deg);
  color: var(--text-primary);
  white-space: pre-wrap;
}

/* Responsive Breakpoints */
@media (max-width: 1024px) {
  .exam-layout {
    grid-template-columns: 1fr;
  }
  .palette-sidebar {
    position: static;
  }
}

@media (max-width: 640px) {
  .header-container {
    flex-wrap: wrap;
  }
  .exam-meta-pill {
    display: none;
  }
  .question-footer {
    flex-direction: column;
    align-items: stretch;
  }
  .footer-nav-group, .footer-status-group {
    justify-content: space-between;
  }
}