/* ============================================
   Grade 5 English Education - Design System
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;500;600;700;800;900&family=Inter:wght@300;400;500;600;700&display=swap');

/* --- CSS Custom Properties --- */
:root {
  /* Colors */
  --bg-primary: #0a1628;
  --bg-secondary: #111d35;
  --bg-card: rgba(255, 255, 255, 0.05);
  --bg-card-hover: rgba(255, 255, 255, 0.1);
  --bg-glass: rgba(255, 255, 255, 0.08);

  --text-primary: #ffffff;
  --text-secondary: #a0aec0;
  --text-muted: #6b7a8d;

  --accent-blue: #4facfe;
  --accent-purple: #a855f7;
  --accent-green: #34d399;
  --accent-orange: #fb923c;
  --accent-pink: #f472b6;
  --accent-cyan: #22d3ee;
  --accent-yellow: #facc15;
  --accent-red: #f87171;

  /* Gradients */
  --grad-blue: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  --grad-purple: linear-gradient(135deg, #a855f7 0%, #6366f1 100%);
  --grad-green: linear-gradient(135deg, #34d399 0%, #06b6d4 100%);
  --grad-orange: linear-gradient(135deg, #fb923c 0%, #f43f5e 100%);
  --grad-pink: linear-gradient(135deg, #f472b6 0%, #a855f7 100%);
  --grad-hero: linear-gradient(135deg, #667eea 0%, #764ba2 100%);

  /* Typography */
  --font-heading: 'Outfit', sans-serif;
  --font-body: 'Inter', sans-serif;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 50%;

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.15);
  --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.25);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.35);
  --shadow-glow-blue: 0 0 30px rgba(79, 172, 254, 0.3);
  --shadow-glow-purple: 0 0 30px rgba(168, 85, 247, 0.3);
  --shadow-glow-green: 0 0 30px rgba(52, 211, 153, 0.3);
  --shadow-glow-orange: 0 0 30px rgba(251, 146, 60, 0.3);

  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-med: 0.3s ease;
  --transition-slow: 0.5s ease;

  /* Layout */
  --max-width: 1200px;
  --nav-height: 70px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-body);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
}

a {
  text-decoration: none;
  color: inherit;
}

ul, ol {
  list-style: none;
}

img {
  max-width: 100%;
  display: block;
}

button {
  cursor: pointer;
  border: none;
  background: none;
  font-family: var(--font-body);
  color: inherit;
}

/* --- Background Decoration --- */
body::before {
  content: '';
  position: fixed;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 20% 50%, rgba(79, 172, 254, 0.05) 0%, transparent 50%),
              radial-gradient(circle at 80% 20%, rgba(168, 85, 247, 0.05) 0%, transparent 50%),
              radial-gradient(circle at 50% 80%, rgba(52, 211, 153, 0.04) 0%, transparent 50%);
  z-index: -1;
  animation: bgFloat 20s ease-in-out infinite alternate;
}

@keyframes bgFloat {
  0% { transform: translate(0, 0); }
  100% { transform: translate(-30px, -20px); }
}

/* --- Navigation --- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(10, 22, 40, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 var(--space-xl);
}

.nav-container {
  max-width: var(--max-width);
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-heading);
  font-weight: 800;
  font-size: 1.4rem;
}

.nav-logo .logo-icon {
  font-size: 1.8rem;
}

.nav-logo .logo-text {
  background: var(--grad-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.nav-link {
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: 0.9rem;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  position: relative;
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
  background: var(--bg-glass);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 3px;
  border-radius: 2px;
  background: var(--grad-hero);
}

.nav-mobile-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: var(--space-sm);
}

.nav-mobile-toggle span {
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition-fast);
}

/* --- Hero Section --- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--nav-height) + var(--space-3xl)) var(--space-xl) var(--space-3xl);
  position: relative;
}

.hero-content {
  max-width: 800px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-xl);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  margin-bottom: var(--space-xl);
  animation: fadeInUp 0.6s ease;
}

.hero h1 {
  font-family: var(--font-heading);
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 900;
  line-height: 1.1;
  margin-bottom: var(--space-lg);
  animation: fadeInUp 0.6s ease 0.1s both;
}

.hero h1 .gradient-text {
  background: var(--grad-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-2xl);
  animation: fadeInUp 0.6s ease 0.2s both;
}

.hero-buttons {
  display: flex;
  gap: var(--space-md);
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeInUp 0.6s ease 0.3s both;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 14px 28px;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  transition: all var(--transition-med);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: var(--grad-hero);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--text-primary);
}

.btn-secondary:hover {
  background: var(--bg-card-hover);
  transform: translateY(-2px);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
}

/* --- Section Layout --- */
.section {
  padding: var(--space-3xl) var(--space-xl);
  max-width: var(--max-width);
  margin: 0 auto;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.section-header h2 {
  font-family: var(--font-heading);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 800;
  margin-bottom: var(--space-md);
}

.section-header p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 600px;
  margin: 0 auto;
}

/* --- Category Cards (Home Page) --- */
.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--space-xl);
}

.category-card {
  position: relative;
  padding: var(--space-2xl);
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.06);
  transition: all var(--transition-med);
  overflow: hidden;
  cursor: pointer;
  text-decoration: none;
  display: block;
}

.category-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  opacity: 0;
  transition: opacity var(--transition-med);
}

.category-card:hover {
  transform: translateY(-8px);
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.12);
}

.category-card:hover::before {
  opacity: 1;
}

.category-card.grammar::before { background: var(--grad-blue); }
.category-card.grammar:hover { box-shadow: var(--shadow-glow-blue); }

.category-card.words::before { background: var(--grad-purple); }
.category-card.words:hover { box-shadow: var(--shadow-glow-purple); }

.category-card.pronunciation::before { background: var(--grad-green); }
.category-card.pronunciation:hover { box-shadow: var(--shadow-glow-green); }

.category-card.vocabulary::before { background: var(--grad-orange); }
.category-card.vocabulary:hover { box-shadow: var(--shadow-glow-orange); }

.card-icon {
  font-size: 3rem;
  margin-bottom: var(--space-lg);
  display: block;
}

.category-card h3 {
  font-family: var(--font-heading);
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
}

.category-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: var(--space-lg);
}

.card-topics {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.card-topic-tag {
  padding: 4px 10px;
  background: var(--bg-glass);
  border-radius: var(--radius-xl);
  font-size: 0.75rem;
  color: var(--text-secondary);
}

/* --- Page Header (Sub Pages) --- */
.page-header {
  padding: calc(var(--nav-height) + var(--space-3xl)) var(--space-xl) var(--space-2xl);
  text-align: center;
  position: relative;
}

.page-header h1 {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 900;
  margin-bottom: var(--space-md);
}

.page-header p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto;
}

.page-header .header-icon {
  font-size: 4rem;
  display: block;
  margin-bottom: var(--space-lg);
}

/* --- Topic Cards --- */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-xl);
}

.topic-card {
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: all var(--transition-med);
  cursor: pointer;
}

.topic-card:hover {
  background: var(--bg-card-hover);
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
}

.topic-card .topic-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  font-weight: 700;
  font-size: 0.85rem;
  margin-bottom: var(--space-md);
}

.topic-card h3 {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
}

.topic-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: var(--space-md);
}

/* Topic Number Colors */
.topic-card.blue .topic-num { background: rgba(79, 172, 254, 0.15); color: var(--accent-blue); }
.topic-card.purple .topic-num { background: rgba(168, 85, 247, 0.15); color: var(--accent-purple); }
.topic-card.green .topic-num { background: rgba(52, 211, 153, 0.15); color: var(--accent-green); }
.topic-card.orange .topic-num { background: rgba(251, 146, 60, 0.15); color: var(--accent-orange); }

/* --- Content Panel (Lesson Detail) --- */
.lesson-panel {
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  margin-bottom: var(--space-xl);
  display: none;
}

.lesson-panel.active {
  display: block;
  animation: fadeInUp 0.4s ease;
}

.lesson-panel h2 {
  font-family: var(--font-heading);
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: var(--space-lg);
}

.lesson-panel h3 {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
  color: var(--accent-cyan);
}

.lesson-content {
  color: var(--text-secondary);
  line-height: 1.8;
}

.lesson-content p {
  margin-bottom: var(--space-md);
}

.lesson-content ul {
  margin-bottom: var(--space-md);
  padding-left: var(--space-xl);
}

.lesson-content ul li {
  list-style: disc;
  margin-bottom: var(--space-sm);
}

.example-box {
  background: rgba(79, 172, 254, 0.08);
  border-left: 3px solid var(--accent-blue);
  padding: var(--space-lg);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: var(--space-md) 0;
}

.example-box.green {
  background: rgba(52, 211, 153, 0.08);
  border-left-color: var(--accent-green);
}

.example-box.purple {
  background: rgba(168, 85, 247, 0.08);
  border-left-color: var(--accent-purple);
}

.example-box.orange {
  background: rgba(251, 146, 60, 0.08);
  border-left-color: var(--accent-orange);
}

.example-label {
  font-weight: 600;
  color: var(--accent-blue);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: var(--space-sm);
  display: block;
}

.example-label.green { color: var(--accent-green); }
.example-label.purple { color: var(--accent-purple); }
.example-label.orange { color: var(--accent-orange); }

.example-sentence {
  font-size: 1rem;
  color: var(--text-primary);
}

.example-sentence .highlight {
  font-weight: 700;
  text-decoration: underline;
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
}

.highlight-blue { color: var(--accent-blue); text-decoration-color: var(--accent-blue); }
.highlight-purple { color: var(--accent-purple); text-decoration-color: var(--accent-purple); }
.highlight-green { color: var(--accent-green); text-decoration-color: var(--accent-green); }
.highlight-orange { color: var(--accent-orange); text-decoration-color: var(--accent-orange); }

/* --- Quiz Section --- */
.quiz-section {
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  margin-top: var(--space-2xl);
}

.quiz-section h3 {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: var(--space-lg);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.quiz-question {
  margin-bottom: var(--space-xl);
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.quiz-question:last-child {
  border-bottom: none;
  margin-bottom: 0;
  padding-bottom: 0;
}

.quiz-question p {
  font-weight: 500;
  margin-bottom: var(--space-md);
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-sm);
}

.quiz-option {
  padding: var(--space-md);
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 0.9rem;
  text-align: left;
}

.quiz-option:hover {
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.15);
}

.quiz-option.correct {
  background: rgba(52, 211, 153, 0.15);
  border-color: var(--accent-green);
  color: var(--accent-green);
}

.quiz-option.wrong {
  background: rgba(248, 113, 113, 0.15);
  border-color: var(--accent-red);
  color: var(--accent-red);
}

.quiz-option.disabled {
  pointer-events: none;
  opacity: 0.6;
}

.quiz-feedback {
  margin-top: var(--space-sm);
  font-size: 0.85rem;
  font-weight: 500;
  display: none;
}

.quiz-feedback.show {
  display: block;
}

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

.quiz-feedback.wrong {
  color: var(--accent-red);
}

/* --- Score Display --- */
.score-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-glass);
  border-radius: var(--radius-md);
  padding: var(--space-md) var(--space-lg);
  margin-top: var(--space-xl);
}

.score-label {
  font-weight: 600;
  color: var(--text-secondary);
}

.score-value {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent-cyan);
}

/* --- Flashcard --- */
.flashcard-container {
  perspective: 1000px;
  margin: var(--space-xl) auto;
  max-width: 500px;
}

.flashcard {
  position: relative;
  width: 100%;
  height: 280px;
  cursor: pointer;
  transition: transform 0.6s ease;
  transform-style: preserve-3d;
}

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

.flashcard-face {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-2xl);
  border-radius: var(--radius-lg);
  backface-visibility: hidden;
  text-align: center;
}

.flashcard-front {
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.flashcard-back {
  background: var(--bg-secondary);
  border: 1px solid rgba(255, 255, 255, 0.1);
  transform: rotateY(180deg);
}

.flashcard-word {
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: var(--space-md);
}

.flashcard-hint {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.flashcard-definition {
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: var(--space-md);
}

.flashcard-example {
  color: var(--text-secondary);
  font-style: italic;
  font-size: 0.9rem;
}

.flashcard-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
  margin-top: var(--space-xl);
}

.flashcard-nav button {
  padding: var(--space-sm) var(--space-lg);
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-weight: 500;
  transition: all var(--transition-fast);
}

.flashcard-nav button:hover {
  background: var(--bg-card-hover);
}

.flashcard-counter {
  color: var(--text-secondary);
  font-weight: 500;
}

/* --- Word Grid --- */
.word-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: var(--space-md);
}

.word-item {
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  transition: all var(--transition-fast);
  cursor: pointer;
}

.word-item:hover {
  background: var(--bg-card-hover);
  transform: translateY(-2px);
}

.word-item .word {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  margin-bottom: var(--space-xs);
}

.word-item .word-type {
  font-size: 0.75rem;
  color: var(--accent-purple);
  margin-bottom: var(--space-sm);
}

.word-item .word-def {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* --- Pronunciation Speaker Button --- */
.speak-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-md);
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-sm);
  color: var(--accent-cyan);
  font-size: 0.85rem;
  transition: all var(--transition-fast);
}

.speak-btn:hover {
  background: rgba(34, 211, 238, 0.15);
  border-color: var(--accent-cyan);
}

.speak-btn.speaking {
  animation: pulse 1s ease infinite;
}

/* --- Tabs --- */
.tab-nav {
  display: flex;
  gap: var(--space-xs);
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
  justify-content: center;
}

.tab-btn {
  padding: var(--space-sm) var(--space-lg);
  background: var(--bg-glass);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: var(--radius-xl);
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.9rem;
  transition: all var(--transition-fast);
}

.tab-btn:hover {
  color: var(--text-primary);
  background: var(--bg-card-hover);
}

.tab-btn.active {
  color: var(--text-primary);
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.15);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
  animation: fadeInUp 0.3s ease;
}

/* --- Search Bar --- */
.search-bar {
  display: flex;
  align-items: center;
  max-width: 500px;
  margin: 0 auto var(--space-2xl);
  background: var(--bg-card);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-xl);
  padding: var(--space-sm) var(--space-lg);
  transition: all var(--transition-fast);
}

.search-bar:focus-within {
  border-color: var(--accent-blue);
  box-shadow: 0 0 0 3px rgba(79, 172, 254, 0.1);
}

.search-bar .search-icon {
  font-size: 1.1rem;
  margin-right: var(--space-sm);
}

.search-bar input {
  flex: 1;
  background: none;
  border: none;
  outline: none;
  color: var(--text-primary);
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: var(--space-sm) 0;
}

.search-bar input::placeholder {
  color: var(--text-muted);
}

/* --- Progress Indicator --- */
.progress-wrap {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-xl);
}

.progress-bar {
  flex: 1;
  height: 8px;
  background: var(--bg-glass);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  border-radius: 4px;
  background: var(--grad-hero);
  transition: width var(--transition-med);
}

.progress-text {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  white-space: nowrap;
}

/* --- Matching Game --- */
.matching-game {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
  max-width: 700px;
  margin: 0 auto;
}

.match-col {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.match-item {
  padding: var(--space-md);
  background: var(--bg-card);
  border: 2px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-sm);
  text-align: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 0.9rem;
}

.match-item:hover {
  background: var(--bg-card-hover);
}

.match-item.selected {
  border-color: var(--accent-blue);
  background: rgba(79, 172, 254, 0.1);
}

.match-item.matched {
  border-color: var(--accent-green);
  background: rgba(52, 211, 153, 0.1);
  pointer-events: none;
  opacity: 0.7;
}

.match-item.wrong {
  border-color: var(--accent-red);
  background: rgba(248, 113, 113, 0.1);
  animation: shake 0.4s ease;
}

/* --- Footer --- */
.footer {
  text-align: center;
  padding: var(--space-2xl) var(--space-xl);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
  margin-top: var(--space-3xl);
}

.footer p {
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* --- Animations --- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.6; }
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-8px); }
  75% { transform: translateX(8px); }
}

.animate-in {
  animation: fadeInUp 0.5s ease both;
}

.animate-in:nth-child(1) { animation-delay: 0.05s; }
.animate-in:nth-child(2) { animation-delay: 0.1s; }
.animate-in:nth-child(3) { animation-delay: 0.15s; }
.animate-in:nth-child(4) { animation-delay: 0.2s; }
.animate-in:nth-child(5) { animation-delay: 0.25s; }
.animate-in:nth-child(6) { animation-delay: 0.3s; }
.animate-in:nth-child(7) { animation-delay: 0.35s; }
.animate-in:nth-child(8) { animation-delay: 0.4s; }

/* --- Responsive --- */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    flex-direction: column;
    background: rgba(10, 22, 40, 0.95);
    backdrop-filter: blur(20px);
    padding: var(--space-md);
    border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  }

  .nav-links.open {
    display: flex;
  }

  .nav-mobile-toggle {
    display: flex;
  }

  .categories-grid {
    grid-template-columns: 1fr;
  }

  .topics-grid {
    grid-template-columns: 1fr;
  }

  .matching-game {
    grid-template-columns: 1fr;
  }

  .quiz-options {
    grid-template-columns: 1fr;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .tab-nav {
    gap: var(--space-xs);
  }

  .tab-btn {
    padding: var(--space-sm) var(--space-md);
    font-size: 0.8rem;
  }
}

@media (max-width: 480px) {
  .section {
    padding: var(--space-2xl) var(--space-md);
  }

  .page-header {
    padding-left: var(--space-md);
    padding-right: var(--space-md);
  }

  .word-grid {
    grid-template-columns: 1fr;
  }
}