/* CSS Variables for Theme System */
:root {
  /* Colors that stay the same for both themes */
  --primary-color: #3b82f6;
  --primary-hover: #2563eb;
  --primary-glow: rgba(59, 130, 246, 0.3);
  --secondary-color: #64748b;
  --accent-color: #06d6a0;
  --accent-glow: rgba(6, 214, 160, 0.3);
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  --cyber-blue: #00d9ff;
  --cyber-purple: #a855f7;
  --cyber-green: #22c55e;
  --neon-pink: #f92672;
  --bg-gradient-primary: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
  --bg-gradient-accent: linear-gradient(135deg, #06d6a0 0%, #059669 100%);
  --bg-gradient-cyber: linear-gradient(135deg, #00d9ff 0%, #a855f7 100%);
  --shadow-neon: 0 0 20px rgba(59, 130, 246, 0.4), 0 0 40px rgba(59, 130, 246, 0.2);
  --shadow-glow: 0 0 30px rgba(6, 214, 160, 0.3), 0 0 60px rgba(6, 214, 160, 0.1);
  
  /* Dark Theme as Default */
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --bg-card: #1e293b;
  --bg-modal: rgba(0, 0, 0, 0.8);
  --bg-glass: rgba(255, 255, 255, 0.1);
  
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --text-white: #ffffff;
  
  --border-color: #334155;
  --border-hover: #475569;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.2);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.2);
  
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
  
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
}

/* Light Theme */
[data-theme="light"] {
  --bg-primary: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --bg-card: rgba(255, 255, 255, 0.95);
  --bg-modal: rgba(15, 23, 42, 0.9);
  --bg-glass: rgba(255, 255, 255, 0.1);
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  
  --border-color: #e2e8f0;
  --border-hover: #cbd5e1;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

/* Font Size Classes */
.font-small { font-size: 0.875rem; }
.font-medium { font-size: 1rem; }
.font-large { font-size: 1.125rem; }

/* Reset and Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-size: var(--font-size-base);
  transition: background-color var(--transition-normal), color var(--transition-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Loading Screen */
.loading-screen {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--bg-primary);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition: opacity var(--transition-slow), visibility var(--transition-slow);
}

.loading-screen.hidden {
  opacity: 0;
  visibility: hidden;
}

.loader {
  width: 80px;
  height: 80px;
  margin-bottom: 2rem;
}

.loader-inner {
  position: relative;
  width: 100%;
  height: 100%;
}

.loader-line-wrap {
  animation: spin 2s cubic-bezier(0.175, 0.885, 0.32, 1.275) infinite;
  box-sizing: border-box;
  height: 50px;
  left: 50%;
  overflow: hidden;
  position: absolute;
  top: 50%;
  transform-origin: 50% 100%;
  width: 2px;
}

.loader-line {
  border: 2px solid transparent;
  border-radius: 100%;
  box-sizing: border-box;
  height: 100px;
  left: 50%;
  margin: 0 0 0 -1px;
  position: absolute;
  top: 50%;
  transform: rotate(0deg);
  width: 100px;
}

.loader-line-wrap:nth-child(1) { animation-delay: -50ms; }
.loader-line-wrap:nth-child(2) { animation-delay: -100ms; }
.loader-line-wrap:nth-child(3) { animation-delay: -150ms; }
.loader-line-wrap:nth-child(4) { animation-delay: -200ms; }
.loader-line-wrap:nth-child(5) { animation-delay: -250ms; }

.loader-line-wrap:nth-child(1) .loader-line { border-color: hsl(0, 80%, 60%); }
.loader-line-wrap:nth-child(2) .loader-line { border-color: hsl(60, 80%, 60%); }
.loader-line-wrap:nth-child(3) .loader-line { border-color: hsl(120, 80%, 60%); }
.loader-line-wrap:nth-child(4) .loader-line { border-color: hsl(180, 80%, 60%); }
.loader-line-wrap:nth-child(5) .loader-line { border-color: hsl(240, 80%, 60%); }

@keyframes spin {
  0%, 15% { transform: rotate(0); }
  25% { transform: rotate(270deg); }
  50% { transform: rotate(270deg); }
  75% { transform: rotate(540deg); }
  100% { transform: rotate(540deg); }
}

.loading-text {
  color: var(--text-secondary);
  font-size: var(--font-size-lg);
  font-weight: 500;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

/* Header */
.header {
  background: var(--bg-card);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--text-primary);
  margin: 0;
}

.clickable-logo {
  cursor: pointer;
  transition: all var(--transition-fast);
  user-select: none;
}

.clickable-logo:hover {
  color: var(--primary-color);
  transform: translateY(-1px);
}

.logo-icon {
  font-size: var(--font-size-3xl);
}

.logo-subtitle {
  font-size: var(--font-size-base);
  font-weight: 400;
  color: var(--text-secondary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Buttons */
.btn-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-card);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: var(--font-size-lg);
}

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

.btn-primary,
.btn-secondary,
.btn-outline {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
  font-size: var(--font-size-base);
  line-height: 1.5;
}

.btn-primary {
  background: var(--primary-color);
  color: var(--text-white);
}

.btn-primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover {
  background: var(--bg-secondary);
  border-color: var(--border-hover);
}

.btn-outline {
  background: transparent;
  color: var(--primary-color);
  border-color: var(--primary-color);
}

.btn-outline:hover {
  background: var(--primary-color);
  color: var(--text-white);
}

.btn-large {
  padding: 1rem 2rem;
  font-size: var(--font-size-lg);
}

.btn-danger {
  color: var(--danger-color);
  border-color: var(--danger-color);
}

.btn-danger:hover {
  background: var(--danger-color);
  color: var(--text-white);
}

.btn-icon .btn-icon {
  font-size: var(--font-size-lg);
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* Theme Toggle */
/* Default dark theme shows moon (light mode toggle) */
.theme-icon-light {
  display: inline;
}

.theme-icon-dark {
  display: none;
}

/* Light theme shows sun (dark mode toggle) */
[data-theme="light"] .theme-icon-light {
  display: none;
}

[data-theme="light"] .theme-icon-dark {
  display: inline;
}

/* Main Container */
.main-container {
  min-height: calc(100vh - 80px);
  padding: 2rem 0;
}

/* Screens */
.screen {
  display: none;
  animation: fadeIn var(--transition-normal);
}

.screen.active {
  display: block;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Hero Section */
.hero {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.hero-title {
  font-size: var(--font-size-4xl);
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 1rem;
  line-height: 1.2;
}

.hero-subtitle {
  font-size: var(--font-size-xl);
  color: var(--text-secondary);
  margin-bottom: 3rem;
  line-height: 1.6;
}

/* Stats Grid */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}

.stat-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.stat-number {
  font-size: var(--font-size-3xl);
  font-weight: 800;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.stat-label {
  color: var(--text-secondary);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-size: var(--font-size-sm);
}

/* Continue Section */
.continue-section {
  margin: 2rem 0;
  text-align: center;
}

.continue-card {
  background: linear-gradient(135deg, var(--primary-color), var(--primary-hover));
  color: var(--text-white);
  padding: 2rem;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  max-width: 500px;
  margin: 0 auto;
}

.continue-card h3 {
  margin-bottom: 0.5rem;
  font-size: var(--font-size-xl);
}

.continue-card p {
  margin-bottom: 1.5rem;
  opacity: 0.9;
}

/* Mode Selection */
.mode-selection {
  margin: 3rem 0;
  text-align: center;
}

.mode-selection h3 {
  color: var(--text-primary);
  margin-bottom: 2rem;
  font-size: var(--font-size-2xl);
}

.mode-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
  max-width: 800px;
  margin: 0 auto;
}

.mode-card {
  background: var(--bg-card);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  cursor: pointer;
  transition: all var(--transition-normal);
  text-align: center;
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-lg);
}

.mode-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.1), transparent);
  transition: left var(--transition-slow);
}

.mode-card:hover {
  transform: translateY(-4px) scale(1.02);
  box-shadow: var(--shadow-neon);
  border-color: var(--primary-color);
  background: rgba(59, 130, 246, 0.05);
}

.mode-card:hover::before {
  left: 100%;
}

.mode-card.selected {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.05);
}

.mode-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.mode-card h4 {
  color: var(--text-primary);
  margin-bottom: 1rem;
  font-size: var(--font-size-xl);
}

.mode-card p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

.mode-features {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  text-align: left;
}

.feature {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* Set Selection Screen */
.set-selection-header {
  text-align: center;
  margin-bottom: 3rem;
}

.set-selection-header h2 {
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  font-size: var(--font-size-3xl);
}

.set-selection-header p {
  color: var(--text-secondary);
  font-size: var(--font-size-lg);
}

/* Study Options - Removed as Study Mode starts directly */

/* Timed Options */
.timed-options {
  margin-bottom: 3rem;
}

.timed-options h3 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: var(--font-size-xl);
  text-align: center;
}

.exam-format-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
  max-width: 700px;
  margin: 0 auto;
}

.exam-format-card {
  background: var(--bg-card);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-md);
}

.exam-format-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(59, 130, 246, 0.1), transparent);
  transition: left 0.5s ease;
}

.exam-format-card:hover {
  transform: translateY(-2px) scale(1.02);
  box-shadow: var(--shadow-glow);
  border-color: var(--accent-color);
  background: rgba(6, 214, 160, 0.05);
}

.exam-format-card:hover::before {
  left: 100%;
}

.exam-format-card.clicked {
  transform: scale(0.98);
  opacity: 0.7;
  pointer-events: none;
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.exam-format-card.clicked::after {
  content: '🚀 Starting...';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: rgba(0, 0, 0, 0.8);
  color: white;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  font-size: var(--font-size-sm);
  z-index: 10;
}

.format-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.format-content h4 {
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  font-size: var(--font-size-lg);
}

.format-content p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  font-size: var(--font-size-sm);
  line-height: 1.5;
}

/* Recommended Section */
.recommended-section {
  margin-bottom: 3rem;
}

.recommended-section h3 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: var(--font-size-xl);
}

/* Recommended card CSS removed - Study Mode starts directly */

/* Sets Section */
.sets-section {
  margin-bottom: 3rem;
}

.sets-section h3 {
  color: var(--text-primary);
  margin-bottom: 1rem;
  font-size: var(--font-size-xl);
}

.progress-summary {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  background: var(--bg-tertiary);
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
}

/* Sets Overview */
.sets-overview {
  margin: 3rem 0;
  text-align: center;
}

.sets-overview h3 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: var(--font-size-xl);
}

.sets-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

/* Review Section */
.review-section {
  margin-bottom: 3rem;
}

.review-section h3 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: var(--font-size-xl);
}

.review-card {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  background: var(--bg-card);
  border: 2px solid var(--warning-color);
  color: var(--text-primary);
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  cursor: pointer;
  transition: all var(--transition-fast);
  max-width: 600px;
  margin: 0 auto;
}

.review-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  background: rgba(245, 158, 11, 0.05);
}

.review-icon {
  font-size: 2.5rem;
  flex-shrink: 0;
  color: var(--warning-color);
}

.review-content {
  flex: 1;
  text-align: left;
}

.review-content h4 {
  margin-bottom: 0.5rem;
  font-size: var(--font-size-lg);
  color: var(--text-primary);
}

.review-content p {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

/* Back Section */
.back-section {
  text-align: center;
  margin-top: 3rem;
}

.set-card {
  background: var(--bg-card);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
}

.set-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-color);
}

.set-card.completed {
  border-color: var(--accent-color);
  background: rgba(16, 185, 129, 0.05);
}

.set-card.in-progress {
  border-color: var(--warning-color);
  background: rgba(245, 158, 11, 0.05);
}

.set-card.special-card {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.05);
}

.set-card.special-card:hover {
  border-color: var(--primary-hover);
  background: rgba(37, 99, 235, 0.1);
}

.set-card.has-saved-progress {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.08);
  position: relative;
}

.set-card.has-saved-progress::before {
  content: '💾';
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  font-size: 1.2rem;
}

.set-status.saved-progress {
  color: var(--primary-color);
  font-weight: 600;
}

.set-title {
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
  font-size: var(--font-size-base);
}

.set-questions {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  margin-bottom: 0.75rem;
}

.set-status {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-size: var(--font-size-sm);
  font-weight: 500;
}

.set-status.completed {
  color: var(--accent-color);
}

.set-status.in-progress {
  color: var(--warning-color);
}

.set-status.not-started {
  color: var(--text-muted);
}

.set-score {
  font-size: var(--font-size-lg);
  font-weight: 700;
  margin-top: 0.5rem;
}

.set-score.high {
  color: var(--accent-color);
}

.set-score.medium {
  color: var(--warning-color);
}

.set-score.low {
  color: var(--danger-color);
}

/* Action Buttons */
.action-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
  margin-bottom: 3rem;
}

/* Exam Options */
.exam-options {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  max-width: 600px;
  margin: 0 auto;
}

.option-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.option-group label {
  font-weight: 500;
  color: var(--text-primary);
  font-size: var(--font-size-sm);
}

.select-field {
  padding: 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: var(--font-size-base);
  transition: all var(--transition-fast);
}

.select-field:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* Exam Screen */
.exam-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2rem;
  flex-wrap: wrap;
  gap: 1rem;
}

.exam-progress {
  flex: 1;
  min-width: 200px;
}

.progress-info {
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  font-size: var(--font-size-sm);
}

.progress-bar {
  height: 8px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
  border-radius: var(--radius-lg);
  transition: width var(--transition-normal);
  width: 0%;
}

.exam-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.timer {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  color: var(--text-primary);
  background: var(--bg-card);
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.score-display {
  font-weight: 600;
  color: var(--accent-color);
  background: var(--bg-card);
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

/* Question Card */
.question-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow-lg);
}

.question-topic {
  display: inline-block;
  background: var(--primary-color);
  color: var(--text-white);
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1.5rem;
}

.question-text {
  font-size: var(--font-size-xl);
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 2rem;
  line-height: 1.6;
}

/* Options Container */
.options-container {
  display: grid;
  gap: 0.75rem;
}

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

.option:hover {
  border-color: var(--primary-color);
  background: var(--bg-card);
  transform: translateX(4px);
}

.option.selected {
  border-color: var(--primary-color);
  background: rgba(37, 99, 235, 0.05);
}

.option.correct {
  border-color: var(--accent-color);
  background: rgba(16, 185, 129, 0.05);
}

.option.incorrect {
  border-color: var(--danger-color);
  background: rgba(239, 68, 68, 0.05);
}

.option-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  background: var(--primary-color);
  color: var(--text-white);
  font-weight: 600;
  font-size: var(--font-size-sm);
  flex-shrink: 0;
}

.option.correct .option-letter {
  background: var(--accent-color);
}

.option.incorrect .option-letter {
  background: var(--danger-color);
}

.option-text {
  flex: 1;
  color: var(--text-primary);
  font-weight: 500;
  line-height: 1.5;
}

/* Question Feedback */
.question-feedback {
  margin-top: 2rem;
  padding: 1.5rem;
  border-radius: var(--radius-lg);
  animation: slideDown var(--transition-normal);
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.feedback-result {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
  font-weight: 600;
  font-size: var(--font-size-lg);
}

.feedback-result.correct {
  color: var(--accent-color);
}

.feedback-result.incorrect {
  color: var(--danger-color);
}

.feedback-explanation {
  color: var(--text-secondary);
  line-height: 1.6;
  font-size: var(--font-size-base);
}

/* Exam Navigation */
.exam-navigation {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 2rem;
}

.nav-left {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.nav-center {
  display: flex;
  gap: 0.5rem;
}

.bookmark-btn.active,
.flag-btn.active {
  background: var(--warning-color);
  color: var(--text-white);
  border-color: var(--warning-color);
}

/* Question Overview */
.question-overview {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 2rem;
  box-shadow: var(--shadow-xl);
  max-width: 90vw;
  max-height: 90vh;
  overflow-y: auto;
  z-index: 1000;
}

.question-overview h4 {
  margin-bottom: 1.5rem;
  color: var(--text-primary);
  font-size: var(--font-size-xl);
}

.overview-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(40px, 1fr));
  gap: 0.5rem;
  margin-bottom: 2rem;
}

.overview-item {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: var(--font-size-sm);
}

.overview-item:hover {
  transform: scale(1.1);
}

.overview-item.current {
  border-color: var(--primary-color);
  background: var(--primary-color);
  color: var(--text-white);
}

.overview-item.answered {
  border-color: var(--accent-color);
  background: rgba(16, 185, 129, 0.1);
  color: var(--accent-color);
}

.overview-item.flagged {
  border-color: var(--warning-color);
  background: rgba(245, 158, 11, 0.1);
  color: var(--warning-color);
}

.overview-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
}

/* Results Screen */
.results-header {
  text-align: center;
  margin-bottom: 3rem;
}

.results-header h2 {
  font-size: var(--font-size-3xl);
  margin-bottom: 2rem;
  color: var(--text-primary);
}

.results-score {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
}

.score-circle {
  position: relative;
  width: 150px;
  height: 150px;
}

.score-svg {
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
}

.score-bg {
  fill: none;
  stroke: var(--bg-tertiary);
  stroke-width: 8;
}

.score-progress {
  fill: none;
  stroke: var(--accent-color);
  stroke-width: 8;
  stroke-linecap: round;
  stroke-dasharray: 314;
  stroke-dashoffset: 314;
  transition: stroke-dashoffset var(--transition-slow);
}

.score-text {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
}

.score-text span {
  font-size: var(--font-size-3xl);
  font-weight: 800;
  color: var(--text-primary);
}

.score-status {
  font-size: var(--font-size-xl);
  font-weight: 600;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-lg);
}

.score-status.pass {
  background: rgba(16, 185, 129, 0.1);
  color: var(--accent-color);
}

.score-status.fail {
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger-color);
}

/* Results Details */
.results-details {
  max-width: 800px;
  margin: 0 auto 3rem;
}

.results-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1.5rem;
  margin-bottom: 3rem;
}

.stat-item {
  text-align: center;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.stat-value {
  display: block;
  font-size: var(--font-size-2xl);
  font-weight: 800;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.stat-label {
  color: var(--text-secondary);
  font-weight: 500;
  font-size: var(--font-size-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.results-breakdown {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.results-breakdown h4 {
  color: var(--text-primary);
  margin-bottom: 1rem;
  font-size: var(--font-size-lg);
}

.topic-result {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--border-color);
}

.topic-result:last-child {
  border-bottom: none;
}

.topic-name {
  font-weight: 500;
  color: var(--text-primary);
  flex: 1;
}

.topic-score {
  font-weight: 600;
  color: var(--text-secondary);
  min-width: 60px;
  text-align: right;
}

.results-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
}

/* Review Screen */
.review-header {
  margin-bottom: 2rem;
}

.review-header h2 {
  color: var(--text-primary);
  margin-bottom: 1.5rem;
  font-size: var(--font-size-2xl);
}

.review-filters {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.filter-btn {
  padding: 0.5rem 1rem;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: var(--font-size-sm);
  font-weight: 500;
}

.filter-btn:hover,
.filter-btn.active {
  background: var(--primary-color);
  color: var(--text-white);
  border-color: var(--primary-color);
}

.review-content {
  margin-bottom: 2rem;
}

.review-question {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
}

.review-question-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.review-question-number {
  font-weight: 600;
  color: var(--primary-color);
}

.review-question-status {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: var(--font-size-sm);
  font-weight: 500;
}

.review-question-status.correct {
  color: var(--accent-color);
}

.review-question-status.incorrect {
  color: var(--danger-color);
}

.review-actions {
  text-align: center;
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--bg-modal);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  backdrop-filter: blur(4px);
}

.modal.active {
  display: flex;
  animation: fadeIn var(--transition-normal);
}

.modal-content {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-xl);
  max-width: 500px;
  width: 90%;
  max-height: 90vh;
  overflow-y: auto;
  animation: slideUp var(--transition-normal);
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.5rem;
  border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
  color: var(--text-primary);
  margin: 0;
  font-size: var(--font-size-xl);
}

.modal-body {
  padding: 1.5rem;
}

.setting-group {
  margin-bottom: 1.5rem;
}

.setting-group:last-child {
  margin-bottom: 0;
}

.setting-label {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  cursor: pointer;
  font-weight: 500;
  color: var(--text-primary);
}

.setting-label input[type="checkbox"] {
  display: none;
}

.checkmark {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-sm);
  position: relative;
  transition: all var(--transition-fast);
}

.setting-label input[type="checkbox"]:checked + .checkmark {
  background: var(--primary-color);
  border-color: var(--primary-color);
}

.setting-label input[type="checkbox"]:checked + .checkmark::after {
  content: "✓";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
  font-size: 12px;
  font-weight: bold;
}

/* Toast */
.toast {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1rem 1.5rem;
  box-shadow: var(--shadow-lg);
  display: none;
  align-items: center;
  gap: 1rem;
  z-index: 3000;
  max-width: 400px;
  animation: slideInRight var(--transition-normal);
}

.toast.active {
  display: flex;
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(100%);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.toast-close {
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: var(--font-size-lg);
  padding: 0;
  line-height: 1;
}

.toast-close:hover {
  color: var(--text-primary);
}

/* Responsive Design */
@media (max-width: 768px) {
  .container {
    padding: 0 0.75rem;
  }
  
  .hero-title {
    font-size: var(--font-size-3xl);
  }
  
  .hero-subtitle {
    font-size: var(--font-size-lg);
  }
  
  .stats-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }
  
  .stat-card {
    padding: 1.5rem;
  }
  
  .action-buttons {
    flex-direction: column;
    align-items: stretch;
  }
  
  .exam-options {
    grid-template-columns: 1fr;
  }
  
  .exam-header {
    flex-direction: column;
    align-items: stretch;
  }
  
  .exam-meta {
    justify-content: center;
  }
  
  .question-card {
    padding: 1.5rem;
  }
  
  .question-text {
    font-size: var(--font-size-lg);
  }
  
  .exam-navigation {
    flex-direction: column;
    gap: 1rem;
  }
  
  .results-stats {
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  }
  
  .results-actions {
    flex-direction: column;
    align-items: stretch;
  }
  
  .review-filters {
    justify-content: center;
  }
  
  .sets-grid {
    grid-template-columns: 1fr;
  }
  
  .set-card {
    padding: 1rem;
  }
  
  .modal-content {
    margin: 1rem;
    width: calc(100% - 2rem);
  }
  
  .toast {
    bottom: 1rem;
    right: 1rem;
    left: 1rem;
    max-width: none;
  }
}

@media (max-width: 480px) {
  .header-content {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }
  
  .logo {
    flex-direction: column;
    gap: 0.25rem;
  }
  
  .logo-subtitle {
    font-size: var(--font-size-sm);
  }
  
  .question-overview {
    margin: 1rem;
    padding: 1.5rem;
    width: calc(100% - 2rem);
    max-width: none;
  }
  
  .overview-grid {
    grid-template-columns: repeat(auto-fill, minmax(35px, 1fr));
  }
  
  .overview-item {
    width: 35px;
    height: 35px;
  }
}

/* Performance Optimizations */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Print Styles */
@media print {
  .header,
  .exam-navigation,
  .action-buttons,
  .results-actions,
  .review-actions {
    display: none !important;
  }
  
  .question-card,
  .review-question {
    break-inside: avoid;
    box-shadow: none;
    border: 1px solid #ccc;
  }
  
  body {
    color: #000;
    background: #fff;
  }
}

/* Reset Section Styles */
.reset-section {
  margin-top: 2rem;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 2px solid var(--danger-color);
  border-radius: 8px;
  text-align: center;
  max-width: 400px;
  margin-left: auto;
  margin-right: auto;
  box-shadow: 0 2px 8px rgba(239, 68, 68, 0.2);
}

.reset-warning {
  margin: 0.75rem 0 0 0;
  font-size: 0.85rem;
  color: var(--text-muted);
  opacity: 0.8;
}

.btn-danger {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  background: var(--danger-color);
  color: white;
  border: 2px solid var(--danger-color);
  font-family: inherit;
}

.btn-danger:hover {
  background: #dc2626;
  border-color: #dc2626;
  transform: translateY(-2px);
}

@media (max-width: 768px) {
  .reset-section {
    margin: 1.5rem 1rem 0 1rem;
    padding: 1rem;
  }
}

/* Legal Footer Styles */
.legal-footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  margin-top: 3rem;
}

.legal-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1rem;
}

.legal-content p {
  margin: 0.5rem 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.5;
}

.disclaimer {
  margin-bottom: 1rem !important;
}

.copyright {
  font-size: 0.8rem !important;
  opacity: 0.8;
}

@media (max-width: 768px) {
  .legal-footer {
    padding: 1.5rem 0;
    margin-top: 2rem;
  }
  
  .legal-content p {
    font-size: 0.8rem;
  }
}