@import url('https://fonts.googleapis.com/css2?family=Kanit:wght@300;400;500;600;700&family=Outfit:wght@300;400;500;600;700;800&display=swap');

/* --- DESIGN SYSTEM & CSS VARIABLES --- */
:root {
  /* Dark Mode Variables (Default) */
  --bg-color: #0b0f19;
  --bg-gradient: radial-gradient(circle at 10% 20%, rgba(99, 102, 241, 0.15) 0%, rgba(0, 0, 0, 0) 40%),
                  radial-gradient(circle at 90% 80%, rgba(139, 92, 246, 0.15) 0%, rgba(0, 0, 0, 0) 50%);
  --card-bg: rgba(17, 24, 39, 0.7);
  --card-hover-bg: rgba(31, 41, 55, 0.8);
  --panel-bg: rgba(22, 30, 49, 0.55);
  --text-primary: #f3f4f6;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(139, 92, 246, 0.4);
  
  --accent-color: #8b5cf6;
  --accent-hover: #7c3aed;
  --accent-glow: rgba(139, 92, 246, 0.4);
  --accent-gradient: linear-gradient(135deg, #6366f1, #8b5cf6);
  
  --success-color: #10b981;
  --success-glow: rgba(16, 185, 129, 0.2);
  --error-color: #ef4444;
  --error-glow: rgba(239, 68, 68, 0.2);
  --warning-color: #f59e0b;
  --warning-glow: rgba(245, 158, 11, 0.2);
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
  --shadow-lg: 0 12px 48px 0 rgba(0, 0, 0, 0.5);
  
  --font-primary: 'Outfit', 'Kanit', sans-serif;
  --border-radius-sm: 8px;
  --border-radius-md: 16px;
  --border-radius-lg: 24px;
}

/* Light Mode Variables */
[data-theme="light"] {
  --bg-color: #f3f4f6;
  --bg-gradient: radial-gradient(circle at 10% 20%, rgba(99, 102, 241, 0.08) 0%, rgba(255, 255, 255, 0) 50%),
                  radial-gradient(circle at 90% 80%, rgba(139, 92, 246, 0.08) 0%, rgba(255, 255, 255, 0) 50%),
                  linear-gradient(to bottom, #f3f4f6, #e5e7eb);
  --card-bg: rgba(255, 255, 255, 0.75);
  --card-hover-bg: rgba(255, 255, 255, 0.9);
  --panel-bg: rgba(243, 244, 246, 0.85);
  --text-primary: #111827;
  --text-secondary: #4b5563;
  --text-muted: #9ca3af;
  --border-color: rgba(0, 0, 0, 0.08);
  --border-hover: rgba(124, 58, 237, 0.4);
  
  --accent-color: #7c3aed;
  --accent-hover: #6d28d9;
  --accent-glow: rgba(124, 58, 237, 0.25);
  --accent-gradient: linear-gradient(135deg, #4f46e5, #7c3aed);
  
  --success-color: #059669;
  --success-glow: rgba(5, 150, 105, 0.15);
  --error-color: #dc2626;
  --error-glow: rgba(220, 38, 38, 0.15);
  --warning-color: #d97706;
  --warning-glow: rgba(217, 119, 6, 0.15);
  
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 8px 32px 0 rgba(31, 38, 135, 0.08);
  --shadow-lg: 0 12px 48px 0 rgba(31, 38, 135, 0.12);
}

/* --- RESET & BASIC STYLES --- */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  transition: background-color 0.3s ease, border-color 0.3s ease, box-shadow 0.3s ease;
}

body {
  font-family: var(--font-primary);
  background-color: var(--bg-color);
  background-image: var(--bg-gradient);
  background-attachment: fixed;
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

/* Custom Scrollbar */
::-webkit-scrollbar {
  width: 10px;
}
::-webkit-scrollbar-track {
  background: var(--bg-color);
}
::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 5px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--accent-color);
}

/* --- CORE LAYOUT & CONTAINER --- */
.container {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 2rem 1.5rem;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

/* Header & Navigation Area */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  padding: 1rem 1.5rem;
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  box-shadow: var(--shadow-sm);
}

.logo-area {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: var(--accent-gradient);
  border-radius: var(--border-radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 800;
  font-size: 1.25rem;
  box-shadow: 0 4px 12px var(--accent-glow);
}

.logo-text h1 {
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.logo-text p {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.nav-controls {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

/* Main Navigation Menu */
.nav-menu {
  display: flex;
  gap: 0.5rem;
  background: var(--panel-bg);
  padding: 0.25rem;
  border-radius: var(--border-radius-sm);
  border: 1px solid var(--border-color);
}

.nav-tab {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-tab:hover {
  color: var(--text-primary);
}

.nav-tab.active {
  background: var(--accent-color);
  color: white;
  box-shadow: 0 2px 8px var(--accent-glow);
}

/* Theme Toggle Button */
.theme-toggle {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  width: 38px;
  height: 38px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}

.theme-toggle:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
  box-shadow: 0 0 10px var(--accent-glow);
}

/* --- GLASS CONTAINER FOR CONTENT SECTIONS --- */
.content-section {
  display: none;
  animation: fadeIn 0.4s ease-in-out forwards;
  flex-grow: 1;
}

.content-section.active {
  display: block;
}

/* Glassmorphism Panel Wrapper (separating background from panel) */
.glass-panel {
  background: var(--card-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-lg);
  box-shadow: var(--shadow-md);
  padding: 2rem;
  margin-bottom: 2rem;
  position: relative;
  overflow: hidden;
}

/* Subtle background glow element for glass panels */
.glass-panel::before {
  content: '';
  position: absolute;
  top: -10%;
  right: -10%;
  width: 300px;
  height: 300px;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.08) 0%, rgba(0,0,0,0) 70%);
  z-index: -1;
  pointer-events: none;
}

/* --- SECTION 1: DASHBOARD --- */
.dashboard-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 1.5rem;
}

@media (max-width: 900px) {
  .dashboard-grid {
    grid-template-columns: 1fr;
  }
}

/* Banner component */
.welcome-banner {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.15) 0%, rgba(139, 92, 246, 0.15) 100%);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.75rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  gap: 1rem;
}

.welcome-text h2 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.welcome-text p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.5;
}

/* Stat Cards */
.stats-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.stat-card {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.25rem;
  text-align: center;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

.stat-val {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--accent-color);
  margin-bottom: 0.25rem;
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Circular Progress Widget */
.progress-widget {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.circle-progress-container {
  position: relative;
  width: 140px;
  height: 140px;
  margin: 1rem 0;
}

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

.circle-bg {
  fill: none;
  stroke: var(--border-color);
  stroke-width: 10;
}

.circle-bar {
  fill: none;
  stroke: var(--accent-color);
  stroke-width: 10;
  stroke-linecap: round;
  stroke-dasharray: 408; /* 2 * pi * 65 */
  stroke-dashoffset: 408;
  transition: stroke-dashoffset 0.8s ease-in-out;
}

.circle-percentage {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 1.6rem;
  font-weight: 800;
}

/* Level Grid */
.level-list-header {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.level-grid {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.level-card {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.25rem;
  display: grid;
  grid-template-columns: auto 1fr auto auto;
  align-items: center;
  gap: 1.5rem;
  position: relative;
}

@media (max-width: 600px) {
  .level-card {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 0.75rem;
  }
}

.level-badge {
  width: 55px;
  height: 55px;
  border-radius: var(--border-radius-sm);
  background: var(--border-color);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-weight: 700;
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.level-badge.unlocked {
  background: var(--accent-gradient);
  color: white;
  border: none;
  box-shadow: 0 4px 10px var(--accent-glow);
}

.level-badge.passed {
  background: var(--success-color);
  color: white;
  border: none;
  box-shadow: 0 4px 10px var(--success-glow);
}

.level-badge .lbl {
  font-size: 0.65rem;
  text-transform: uppercase;
  font-weight: 500;
  opacity: 0.8;
}

.level-badge .num {
  font-size: 1.2rem;
  line-height: 1.1;
}

.level-info h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

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

.level-status-tag {
  padding: 0.25rem 0.75rem;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  background: var(--border-color);
  color: var(--text-secondary);
  border: 1px solid var(--border-color);
  justify-self: end;
  width: fit-content;
}

.level-card.passed .level-status-tag {
  background: rgba(16, 185, 129, 0.1);
  color: var(--success-color);
  border-color: rgba(16, 185, 129, 0.3);
}

.level-card.unlocked:not(.passed) .level-status-tag {
  background: rgba(139, 92, 246, 0.1);
  color: var(--accent-color);
  border-color: rgba(139, 92, 246, 0.3);
}

.level-card.locked .level-status-tag {
  background: rgba(107, 114, 128, 0.1);
  color: var(--text-muted);
}

.btn-start-level {
  background: var(--accent-color);
  color: white;
  border: none;
  padding: 0.65rem 1.25rem;
  border-radius: var(--border-radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  box-shadow: 0 4px 12px var(--accent-glow);
}

.btn-start-level:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px var(--accent-glow);
}

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

/* TOEIC Weighting and Explanation Section */
.toeic-info-card {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.5rem;
}

.toeic-info-card h3 {
  font-size: 1.25rem;
  margin-bottom: 0.75rem;
  font-weight: 600;
}

.toeic-info-card p {
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
}

/* Simple CSS-based chart showing weighting */
.chart-container {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.chart-bar-row {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.chart-bar-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.75rem;
  font-weight: 600;
}

.chart-bar-outer {
  width: 100%;
  height: 12px;
  background: var(--border-color);
  border-radius: 6px;
  overflow: hidden;
}

.chart-bar-inner {
  height: 100%;
  background: var(--accent-gradient);
  border-radius: 6px;
  width: 0%;
  transition: width 1.5s cubic-bezier(0.1, 1, 0.1, 1);
}

.chart-bar-inner.animate {
  width: var(--target-width);
}

/* --- SECTION 2: STUDY GUIDE --- */
.guide-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1rem;
}

.guide-tab-btn {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
}

.guide-tab-btn:hover {
  color: var(--text-primary);
  border-color: var(--accent-color);
}

.guide-tab-btn.active {
  background: var(--accent-color);
  color: white;
  border-color: var(--accent-color);
}

.guide-tab-content {
  display: none;
  animation: fadeIn 0.3s ease;
}

.guide-tab-content.active {
  display: block;
}

.guide-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

@media (max-width: 768px) {
  .guide-grid {
    grid-template-columns: 1fr;
  }
}

.guide-card {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.5rem;
}

.guide-card h3 {
  font-size: 1.2rem;
  margin-bottom: 1rem;
  color: var(--accent-color);
  border-bottom: 1px dashed var(--border-color);
  padding-bottom: 0.5rem;
}

.suffix-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

.suffix-table th, .suffix-table td {
  padding: 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}

.suffix-table th {
  font-weight: 600;
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.02);
}

.suffix-table tr:hover {
  background: rgba(255, 255, 255, 0.01);
}

.suffix-tag {
  display: inline-block;
  background: rgba(139, 92, 246, 0.1);
  color: var(--accent-color);
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  font-family: monospace;
  font-weight: 700;
}

/* Strategies lists */
.strategy-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.strategy-list li {
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--text-secondary);
  position: relative;
  padding-left: 1.5rem;
}

.strategy-list li::before {
  content: '✦';
  position: absolute;
  left: 0;
  color: var(--accent-color);
  font-weight: 700;
}

.strategy-list strong {
  color: var(--text-primary);
}

/* --- SECTION 3: YOUTUBE HUB --- */
.youtube-search-bar {
  display: flex;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.search-input {
  flex-grow: 1;
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.75rem 1.25rem;
  border-radius: var(--border-radius-sm);
  font-size: 0.9rem;
}

.search-input:focus {
  outline: none;
  border-color: var(--accent-color);
  box-shadow: 0 0 10px var(--accent-glow);
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
}

.video-card {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
}

.video-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-color);
  box-shadow: var(--shadow-md);
}

.video-thumbnail-wrapper {
  position: relative;
  width: 100%;
  aspect-ratio: 16/9;
  background: #000;
  cursor: pointer;
  overflow: hidden;
}

.video-thumbnail {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.85;
  transition: transform 0.5s ease;
}

.video-card:hover .video-thumbnail {
  transform: scale(1.05);
  opacity: 1;
}

.play-overlay {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 60px;
  height: 60px;
  background: rgba(139, 92, 246, 0.85);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 1.5rem;
  box-shadow: 0 4px 15px rgba(0,0,0,0.5);
  transition: background 0.3s, transform 0.3s;
}

.video-card:hover .play-overlay {
  background: var(--accent-color);
  transform: translate(-50%, -50%) scale(1.1);
}

.video-duration {
  position: absolute;
  bottom: 8px;
  right: 8px;
  background: rgba(0, 0, 0, 0.8);
  color: white;
  padding: 0.2rem 0.5rem;
  font-size: 0.75rem;
  border-radius: 4px;
  font-weight: 500;
}

.video-content {
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.video-title {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 0.5rem;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  height: 2.8rem;
}

.video-meta {
  font-size: 0.75rem;
  color: var(--text-secondary);
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.video-bullets {
  list-style: none;
  font-size: 0.8rem;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  border-top: 1px solid var(--border-color);
  padding-top: 0.75rem;
  margin-top: auto;
}

.video-bullets li {
  position: relative;
  padding-left: 1rem;
}

.video-bullets li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--accent-color);
}

/* --- SECTION 4: QUIZ INTERFACE (FOCUS MODE) --- */
.quiz-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}

.quiz-title-info h2 {
  font-size: 1.4rem;
  font-weight: 700;
}

.quiz-timer {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text-primary);
  background: var(--panel-bg);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius-sm);
  border: 1px solid var(--border-color);
}

.quiz-timer.low-time {
  color: var(--error-color);
  border-color: var(--error-color);
  box-shadow: 0 0 10px var(--error-glow);
  animation: pulse 1s infinite alternate;
}

.btn-flag {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  font-weight: 600;
}

.btn-flag:hover {
  border-color: var(--warning-color);
  color: var(--warning-color);
}

.btn-flag.flagged {
  background: rgba(245, 158, 11, 0.15);
  border-color: var(--warning-color);
  color: var(--warning-color);
}

/* Progress bar inside quiz */
.quiz-progress-wrapper {
  margin-bottom: 2rem;
}

.quiz-progress-info {
  display: flex;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.quiz-progress-outer {
  width: 100%;
  height: 8px;
  background: var(--border-color);
  border-radius: 4px;
  overflow: hidden;
}

.quiz-progress-inner {
  height: 100%;
  background: var(--accent-gradient);
  width: 0%;
  border-radius: 4px;
  transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Main quiz content layout (Split screen: Question vs Nav map) */
.quiz-layout {
  display: grid;
  grid-template-columns: 3fr 1fr;
  gap: 1.5rem;
}

@media (max-width: 850px) {
  .quiz-layout {
    grid-template-columns: 1fr;
  }
}

.question-card {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 2rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.question-text {
  font-size: 1.25rem;
  line-height: 1.6;
  font-weight: 500;
  padding: 0.5rem 0;
  letter-spacing: -0.01em;
}

.question-text span.blank-line {
  display: inline-block;
  min-width: 100px;
  border-bottom: 2px solid var(--accent-color);
  margin: 0 0.5rem;
  text-align: center;
  font-weight: 700;
  color: var(--accent-color);
}

.options-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.option-btn {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 1rem 1.25rem;
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  text-align: left;
  font-size: 1rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  font-weight: 500;
}

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

.option-btn.selected {
  background: rgba(139, 92, 246, 0.15);
  border-color: var(--accent-color);
  box-shadow: 0 0 12px var(--accent-glow);
  font-weight: 600;
}

.option-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--border-color);
  font-size: 0.85rem;
  font-weight: 700;
  flex-shrink: 0;
  color: var(--text-secondary);
}

.option-btn.selected .option-letter {
  background: var(--accent-color);
  color: white;
}

/* Quiz Quick Jump Grid */
.quiz-sidebar {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.sidebar-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.quiz-jump-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.5rem;
}

.jump-btn {
  aspect-ratio: 1;
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  border-radius: 6px;
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.jump-btn:hover {
  border-color: var(--accent-color);
  color: var(--text-primary);
}

.jump-btn.current {
  border-color: var(--accent-color);
  box-shadow: 0 0 8px var(--accent-glow);
  color: var(--accent-color);
}

.jump-btn.answered {
  background: rgba(139, 92, 246, 0.1);
  border-color: rgba(139, 92, 246, 0.4);
  color: var(--accent-color);
}

.jump-btn.flagged::after {
  content: '';
  position: absolute;
  top: 2px;
  right: 2px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--warning-color);
}

/* Quiz Controls at bottom */
.quiz-controls {
  display: flex;
  justify-content: space-between;
  margin-top: 1.5rem;
}

.btn-quiz-nav {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.75rem 1.5rem;
  border-radius: var(--border-radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.btn-quiz-nav:hover:not(:disabled) {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

.btn-quiz-nav:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-submit-quiz {
  background: var(--success-color);
  color: white;
  border: none;
  padding: 0.75rem 1.5rem;
  border-radius: var(--border-radius-sm);
  font-weight: 700;
  font-size: 0.9rem;
  cursor: pointer;
  box-shadow: 0 4px 12px var(--success-glow);
}

.btn-submit-quiz:hover {
  background: #059669;
  box-shadow: 0 6px 16px var(--success-glow);
}

/* --- SECTION 5: QUIZ RESULTS --- */
.results-summary-card {
  text-align: center;
  padding: 3rem 2rem;
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  margin-bottom: 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.results-badge-container {
  width: 150px;
  height: 150px;
  border-radius: 50%;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  margin-bottom: 1.5rem;
  border: 5px solid var(--border-color);
}

.results-badge-container.passed {
  border-color: var(--success-color);
  box-shadow: 0 0 25px var(--success-glow);
  background: rgba(16, 185, 129, 0.05);
}

.results-badge-container.failed {
  border-color: var(--error-color);
  box-shadow: 0 0 25px var(--error-glow);
  background: rgba(239, 68, 68, 0.05);
}

.results-score {
  font-size: 2.8rem;
  font-weight: 800;
}

.results-score-lbl {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 600;
  text-transform: uppercase;
}

.results-msg-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.results-msg-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  max-width: 500px;
  line-height: 1.6;
  margin-bottom: 2rem;
}

.results-action-row {
  display: flex;
  gap: 1rem;
}

.btn-action-primary {
  background: var(--accent-gradient);
  color: white;
  border: none;
  padding: 0.75rem 1.75rem;
  border-radius: var(--border-radius-sm);
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 12px var(--accent-glow);
}

.btn-action-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 16px var(--accent-glow);
}

.btn-action-secondary {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.75rem 1.75rem;
  border-radius: var(--border-radius-sm);
  font-weight: 600;
  cursor: pointer;
}

.btn-action-secondary:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

/* Detailed Explanations section */
.review-header {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.review-filter-btn {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.35rem 0.75rem;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
}

.review-filter-btn.active {
  background: var(--accent-color);
  color: white;
  border-color: var(--accent-color);
}

.review-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.review-card-item {
  background: var(--panel-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.review-card-item.correct {
  border-left: 5px solid var(--success-color);
}

.review-card-item.incorrect {
  border-left: 5px solid var(--error-color);
}

.review-question-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1rem;
}

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

.review-q-text {
  font-size: 1.05rem;
  font-weight: 500;
  line-height: 1.5;
  flex-grow: 1;
}

.review-status-icon {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 0.8rem;
  flex-shrink: 0;
}

.review-card-item.correct .review-status-icon {
  background: var(--success-color);
}

.review-card-item.incorrect .review-status-icon {
  background: var(--error-color);
}

.review-options-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 0.5rem;
}

.review-opt-box {
  padding: 0.75rem 1rem;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.review-opt-box.correct {
  background: rgba(16, 185, 129, 0.1);
  border-color: var(--success-color);
  color: var(--success-color);
  font-weight: 600;
}

.review-opt-box.user-incorrect {
  background: rgba(239, 68, 68, 0.1);
  border-color: var(--error-color);
  color: var(--error-color);
  font-weight: 600;
}

.explanation-drawer {
  background: rgba(255, 255, 255, 0.01);
  border-top: 1px dashed var(--border-color);
  padding-top: 1rem;
  margin-top: 0.5rem;
}

.explanation-title {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-color);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
}

.explanation-body {
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--text-secondary);
}

.explanation-tag {
  display: inline-block;
  background: var(--border-color);
  color: var(--text-secondary);
  font-size: 0.7rem;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  font-weight: 600;
  margin-top: 0.75rem;
}

/* --- YOUTUBE POPUP MODAL --- */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(0, 0, 0, 0.85);
  backdrop-filter: blur(8px);
  z-index: 1000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  animation: fadeIn 0.3s ease;
}

.modal-overlay.active {
  display: flex;
}

.modal-content {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-lg);
  max-width: 800px;
  width: 100%;
  box-shadow: var(--shadow-lg);
  overflow: hidden;
  position: relative;
  display: flex;
  flex-direction: column;
}

.modal-close-btn {
  position: absolute;
  top: 1rem;
  right: 1rem;
  background: rgba(0, 0, 0, 0.5);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: white;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  z-index: 1010;
}

.modal-close-btn:hover {
  background: var(--accent-color);
}

.modal-video-wrapper {
  width: 100%;
  aspect-ratio: 16/9;
  background: #000;
}

.modal-video-wrapper iframe {
  width: 100%;
  height: 100%;
  border: none;
}

.modal-details {
  padding: 1.5rem;
}

.modal-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.modal-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* --- KEYFRAME ANIMATIONS --- */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  from {
    opacity: 1;
  }
  to {
    opacity: 0.6;
  }
}

/* --- FOOTER --- */
footer {
  margin-top: auto;
  text-align: center;
  padding: 2rem 0;
  font-size: 0.8rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  width: 100%;
}
footer a {
  color: var(--text-secondary);
  text-decoration: none;
}
footer a:hover {
  color: var(--accent-color);
}