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

:root {
  --bg-primary: #0a0a0f;
  --bg-secondary: #12121a;
  --bg-tertiary: #1a1a2e;
  --glass-surface: rgba(255,255,255,0.03);
  --glass-surface-hover: rgba(255,255,255,0.06);
  --glass-border: rgba(255,255,255,0.08);
  --glass-border-hover: rgba(255,255,255,0.15);
  --glass-blur: blur(24px);
  --accent: #6c5ce7;
  --accent-2: #00cec9;
  --accent-3: #fd79a8;
  --accent-4: #e17055;
  --accent-5: #fdcb6e;
  --gradient-hero: linear-gradient(135deg, #6c5ce7, #00cec9);
  --gradient-warm: linear-gradient(135deg, #e17055, #fdcb6e);
  --gradient-pink: linear-gradient(135deg, #fd79a8, #6c5ce7);
  --text-primary: #f8f9fa;
  --text-secondary: rgba(255,255,255,0.65);
  --text-muted: rgba(255,255,255,0.35);
  --success: #00b894;
  --error: #d63031;
  --warning: #fdcb6e;
  --max-width: 1200px;
  --topic-width: 1400px;
  --nav-height: 64px;
  --glass-radius: 16px;
  --card-radius: 12px;
  --button-radius: 8px;
  --transition-fast: 200ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-med: 400ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 600ms cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
  --bg-primary: #f8f9fa;
  --bg-secondary: #ffffff;
  --bg-tertiary: #e9ecef;
  --glass-surface: rgba(0,0,0,0.02);
  --glass-surface-hover: rgba(0,0,0,0.05);
  --glass-border: rgba(0,0,0,0.08);
  --glass-border-hover: rgba(0,0,0,0.15);
  --text-primary: #0a0a0f;
  --text-secondary: rgba(0,0,0,0.65);
  --text-muted: rgba(0,0,0,0.35);
}

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

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: var(--glass-border); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--glass-border-hover); }

::selection { background: var(--accent); color: white; }

a { color: var(--accent-2); text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--accent); }

code, pre {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
}

.glass {
  background: var(--glass-surface);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: 1px solid var(--glass-border);
  border-radius: var(--glass-radius);
}

.glass-hover {
  transition: all var(--transition-med);
}
.glass-hover:hover {
  background: var(--glass-surface-hover);
  border-color: var(--glass-border-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(108,92,231,0.1);
}

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.topic-container {
  max-width: var(--topic-width);
  margin: 0 auto;
  padding: 0 32px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border: none;
  border-radius: var(--button-radius);
  font-family: inherit;
  font-size: 0.9375rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-med);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: var(--gradient-hero);
  color: white;
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(108,92,231,0.3);
}

.btn-ghost {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--glass-border);
}
.btn-ghost:hover {
  border-color: var(--glass-border-hover);
  background: var(--glass-surface);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
}

.section {
  padding: 100px 0;
  position: relative;
}

.section-label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent);
  margin-bottom: 12px;
}

.section-title {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 16px;
}

.section-subtitle {
  font-size: clamp(1rem, 1.5vw, 1.125rem);
  color: var(--text-secondary);
  max-width: 600px;
  line-height: 1.6;
}

/* Navbar */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  z-index: 1000;
  background: rgba(10, 10, 15, 0.8);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-bottom: 1px solid var(--glass-border);
  transition: all var(--transition-med);
}

.navbar.scrolled {
  box-shadow: 0 4px 32px rgba(0,0,0,0.3);
}

.navbar-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.navbar-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--text-primary);
}

.navbar-logo svg {
  width: 28px;
  height: 28px;
}

.navbar-links {
  display: flex;
  align-items: center;
  gap: 24px;
  list-style: none;
}

.navbar-links a {
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  transition: color var(--transition-fast);
}

.navbar-links a:hover {
  color: var(--text-primary);
}

.theme-toggle {
  width: 40px;
  height: 40px;
  border: 1px solid var(--glass-border);
  border-radius: 50%;
  background: var(--glass-surface);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  font-size: 1.125rem;
}

.theme-toggle:hover {
  border-color: var(--glass-border-hover);
  color: var(--text-primary);
}

/* Hero Section */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
  padding-top: var(--nav-height);
}

.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}



.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 900px;
  padding: 0 24px;
}

.hero-title {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto 40px;
  line-height: 1.6;
}

.hero-cta {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.hero-scroll-indicator {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--text-muted);
  font-size: 0.75rem;
  z-index: 2;
  animation: float 2s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(-8px); }
}

.hero-scroll-indicator .mouse {
  width: 24px;
  height: 38px;
  border: 2px solid var(--text-muted);
  border-radius: 12px;
  position: relative;
}

.hero-scroll-indicator .mouse::after {
  content: '';
  position: absolute;
  top: 6px;
  left: 50%;
  transform: translateX(-50%);
  width: 3px;
  height: 8px;
  background: var(--text-muted);
  border-radius: 2px;
  animation: scrollWheel 1.5s ease-in-out infinite;
}

@keyframes scrollWheel {
  0% { opacity: 1; transform: translateX(-50%) translateY(0); }
  100% { opacity: 0; transform: translateX(-50%) translateY(12px); }
}

/* Topic Cards */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
}

.topic-card {
  position: relative;
  padding: 32px;
  cursor: pointer;
  overflow: hidden;
}

.topic-card.active {
  border-color: var(--glass-border-hover);
}

.topic-card.locked {
  opacity: 0.55;
  cursor: not-allowed;
  filter: grayscale(0.6);
  border-color: var(--glass-border);
}

.topic-card.locked:hover {
  transform: none;
  box-shadow: none;
}

.topic-card.locked .lock-icon {
  font-size: 2.5rem;
  opacity: 0.9;
  z-index: 2;
  filter: drop-shadow(0 0 8px rgba(0,0,0,0.3));
}

.topic-card.locked .topic-card-icon {
  background: var(--glass-surface) !important;
  opacity: 0.5;
}

.topic-card-icon {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 16px;
}

.topic-card-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.topic-card-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 16px;
}

.topic-card-meta {
  display: flex;
  gap: 12px;
  font-size: 0.75rem;
  color: var(--text-muted);
}

.topic-card-meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.topic-card-badge {
  position: absolute;
  top: 16px;
  right: 16px;
  padding: 4px 12px;
  border-radius: 20px;
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.topic-card-badge.beginner { background: rgba(0, 206, 201, 0.15); color: var(--accent-2); }
.topic-card-badge.intermediate { background: rgba(253, 121, 168, 0.15); color: var(--accent-3); }
.topic-card-badge.advanced { background: rgba(225, 112, 85, 0.15); color: var(--accent-4); }

.topic-card .lock-icon {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 2rem;
  opacity: 0.6;
}

.topic-card-glow {
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at center, var(--card-glow, var(--accent)), transparent 60%);
  opacity: 0;
  transition: opacity var(--transition-med);
  pointer-events: none;
}

.topic-card:hover .topic-card-glow {
  opacity: 0.08;
}

.topic-card-progress {
  height: 3px;
  background: var(--glass-border);
  border-radius: 2px;
  margin-bottom: 12px;
  overflow: hidden;
}

.topic-card-progress-bar {
  height: 100%;
  border-radius: 2px;
  transition: width 0.6s ease-out;
}

/* Stats Bar */
.stats-bar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 24px;
  padding: 60px 0;
}

.stat-item {
  text-align: center;
  padding: 32px 24px;
}

.stat-number {
  font-size: clamp(2rem, 4vw, 3.5rem);
  font-weight: 800;
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1;
  margin-bottom: 8px;
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Knowledge Tree */
.domain-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
}

.domain-card {
  background: var(--glass-surface);
  border: 1px solid var(--glass-border);
  border-radius: 10px;
  padding: 16px 12px;
  text-align: center;
  position: relative;
  transition: all 0.3s ease;
}

.domain-card {
  border-color: var(--glass-border);
}

.domain-icon {
  font-size: 1.5rem;
  margin-bottom: 6px;
  line-height: 1;
}

.domain-name {
  font-size: 0.6875rem;
  font-weight: 500;
  color: var(--text-primary);
  line-height: 1.3;
}

/* Roadmap Timeline */
.roadmap-wrapper {
  position: relative;
  overflow: hidden;
  padding: 40px 0;
}

.roadmap-track {
  display: flex;
  gap: 0;
  padding: 40px 0;
  position: relative;
}

.roadmap-node {
  flex-shrink: 0;
  width: 280px;
  padding: 24px;
  position: relative;
}

.roadmap-node::before {
  content: '';
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent);
  border: 3px solid var(--bg-primary);
  z-index: 2;
}

.roadmap-node.completed::before { background: var(--success); }
.roadmap-node.current::before { background: var(--accent-2); box-shadow: 0 0 16px rgba(0,206,201,0.4); }
.roadmap-node.future::before { background: var(--bg-tertiary); border-color: var(--glass-border); }

.roadmap-connector {
  position: absolute;
  top: 8px;
  left: 50%;
  right: -50%;
  height: 2px;
  background: var(--glass-border);
  z-index: 1;
}

.roadmap-node:last-child .roadmap-connector { display: none; }

.roadmap-node.current .roadmap-connector { background: var(--gradient-hero); }

.roadmap-node-title {
  font-size: 1rem;
  font-weight: 600;
  margin-top: 24px;
  margin-bottom: 4px;
}

.roadmap-node-desc {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.roadmap-node-number {
  position: absolute;
  top: -8px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.625rem;
  font-weight: 700;
  background: var(--bg-primary);
  padding: 0 4px;
  z-index: 3;
}

/* Progress Dashboard */
.progress-dashboard {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.progress-chart-container {
  padding: 24px;
  min-height: 300px;
}

.progress-chart-container svg {
  width: 100%;
  height: 100%;
}

/* Topic Page Specific */
.topic-hero {
  min-height: 60vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding-top: var(--nav-height);
}

.topic-hero-content {
  position: relative;
  z-index: 2;
  max-width: 700px;
}

.topic-hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 20px;
}

.topic-hero-badge.beginner { background: rgba(0, 206, 201, 0.15); color: var(--accent-2); }
.topic-hero-badge.intermediate { background: rgba(253, 121, 168, 0.15); color: var(--accent-3); }
.topic-hero-badge.advanced { background: rgba(225, 112, 85, 0.15); color: var(--accent-4); }

.topic-hero h1 {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 16px;
}

.topic-hero p {
  font-size: 1.125rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 32px;
}

.topic-hero-stats {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.topic-hero-stat {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-muted);
}

.topic-hero-stat strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* Subtopic Sections */
.subtopic-section {
  min-height: 100vh;
  padding: 80px 0;
  position: relative;
}

.subtopic-section:nth-child(odd) {
  background: var(--bg-secondary);
}

.subtopic-header {
  margin-bottom: 48px;
  position: relative;
  z-index: 2;
}

.subtopic-number {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 8px;
}

.subtopic-title {
  font-size: clamp(1.5rem, 3vw, 2.5rem);
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 12px;
}

.subtopic-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 600px;
}

.subtopic-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  align-items: start;
  position: relative;
  z-index: 2;
}

.subtopic-content.single { grid-template-columns: 1fr; }

.subtopic-visual {
  background: var(--glass-surface);
  border: 1px solid var(--glass-border);
  border-radius: var(--glass-radius);
  overflow: hidden;
  min-height: 300px;
  position: relative;
}

.subtopic-visual canvas,
.subtopic-visual svg {
  width: 100%;
  height: 100%;
}

.subtopic-visual.three-container {
  min-height: 400px;
}

.subtopic-text {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.subtopic-text p {
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

.subtopic-text .highlight {
  background: rgba(108, 92, 231, 0.1);
  border-left: 3px solid var(--accent);
  padding: 16px 20px;
  border-radius: 0 8px 8px 0;
  color: var(--text-primary);
}

.subtopic-text .analogy {
  background: rgba(0, 206, 201, 0.08);
  border: 1px solid rgba(0, 206, 201, 0.2);
  padding: 16px 20px;
  border-radius: 8px;
  font-style: italic;
  color: var(--accent-2);
}

.code-block {
  background: var(--bg-tertiary);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  padding: 20px;
  overflow-x: auto;
  font-size: 0.8125rem;
  line-height: 1.6;
}

.code-block .line {
  display: block;
  opacity: 0;
  transform: translateX(-10px);
}

.code-block .line.highlighted {
  background: rgba(108, 92, 231, 0.1);
  border-left: 2px solid var(--accent);
  padding-left: 12px;
}

.code-block .keyword { color: #c792ea; }
.code-block .type { color: #82aaff; }
.code-block .string { color: #c3e88d; }
.code-block .comment { color: #546e7a; font-style: italic; }
.code-block .number { color: #f78c6c; }
.code-block .annotation { color: #ffcb6b; }

/* Interactive Demo */
.interactive-demo {
  background: var(--glass-surface);
  border: 1px solid var(--glass-border);
  border-radius: var(--glass-radius);
  overflow: hidden;
}

.interactive-demo-header {
  padding: 16px 20px;
  border-bottom: 1px solid var(--glass-border);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.interactive-demo-body {
  padding: 24px;
  min-height: 200px;
}

.interactive-demo .controls {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.interactive-demo .control-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.interactive-demo .control-group label {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 500;
}

.interactive-demo input[type="range"] {
  width: 140px;
  height: 4px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--bg-tertiary);
  border-radius: 2px;
  outline: none;
}

.interactive-demo input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
}

.interactive-demo .demo-canvas {
  width: 100%;
  min-height: 200px;
  background: var(--bg-tertiary);
  border-radius: 8px;
}

/* Floating TOC */
/* Quiz */
.quiz-container {
  max-width: 700px;
  margin: 0 auto;
}

.quiz-progress {
  display: flex;
  gap: 8px;
  margin-bottom: 32px;
}

.quiz-progress-dot {
  flex: 1;
  height: 4px;
  border-radius: 2px;
  background: var(--glass-border);
  transition: all var(--transition-med);
}

.quiz-progress-dot.answered {
  background: var(--accent);
}

.quiz-progress-dot.wrong {
  background: var(--error);
}

.quiz-question {
  margin-bottom: 24px;
}

.quiz-question h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 20px;
  line-height: 1.4;
}

.quiz-options {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.quiz-option {
  padding: 16px 20px;
  background: var(--glass-surface);
  border: 1px solid var(--glass-border);
  border-radius: var(--card-radius);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 0.9375rem;
  opacity: 0;
  transform: translateX(-20px);
}

.quiz-option:hover {
  background: var(--glass-surface-hover);
  border-color: var(--glass-border-hover);
}

.quiz-option.selected {
  border-color: var(--accent);
  background: rgba(108, 92, 231, 0.1);
}

.quiz-option.correct {
  border-color: var(--success);
  background: rgba(0, 184, 148, 0.1);
}

.quiz-option.wrong {
  border-color: var(--error);
  background: rgba(214, 48, 49, 0.1);
  animation: shake 0.4s ease-in-out;
}

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

.quiz-option .option-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background: var(--bg-tertiary);
  font-size: 0.75rem;
  font-weight: 600;
  margin-right: 12px;
}

.quiz-option.correct .option-letter {
  background: var(--success);
  color: white;
}

.quiz-option.wrong .option-letter {
  background: var(--error);
  color: white;
}

.quiz-feedback {
  padding: 16px 20px;
  border-radius: var(--card-radius);
  margin-top: 16px;
  font-size: 0.875rem;
  opacity: 0;
}

.quiz-feedback.show {
  opacity: 1;
}

.quiz-feedback.correct {
  background: rgba(0, 184, 148, 0.1);
  border: 1px solid rgba(0, 184, 148, 0.2);
  color: var(--success);
}

.quiz-feedback.wrong {
  background: rgba(214, 48, 49, 0.1);
  border: 1px solid rgba(214, 48, 49, 0.2);
  color: var(--error);
}

/* Summary Mind Map */
.summary-mindmap {
  background: var(--glass-surface);
  border: 1px solid var(--glass-border);
  border-radius: var(--glass-radius);
  min-height: 500px;
  position: relative;
  overflow: hidden;
}

.summary-mindmap svg {
  width: 100%;
  height: 100%;
}

.summary-key-points {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-top: 32px;
}

.key-point {
  padding: 20px;
  opacity: 0;
  transform: translateY(20px);
}

.key-point-number {
  font-size: 0.6875rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 8px;
}

.key-point-text {
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* Confetti */
/* Loading States */
.loading-spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--glass-border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Responsive */
@media (max-width: 1024px) {
  .subtopic-content { grid-template-columns: 1fr; }
  .progress-dashboard { grid-template-columns: 1fr; }
  .topics-grid { grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); }
}

@media (max-width: 768px) {
  .navbar-links a:not(.theme-toggle) { display: none; }
  .hero-title { font-size: clamp(2rem, 8vw, 3rem); }
  .section { padding: 60px 0; }
  .stats-bar { grid-template-columns: 1fr 1fr; }
  .topics-grid { grid-template-columns: 1fr; }
  .topic-container { padding: 0 20px; }
  .container { padding: 0 20px; }
}

@media (max-width: 480px) {
  .stats-bar { grid-template-columns: 1fr; }
  .quiz-option { font-size: 0.875rem; }
}