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

:root {
  --bg: #0A0A0A;
  --card: #161616;
  --orange: #3B82F6;
  --orange-dim: rgba(59, 130, 246, 0.15);
  --orange-border: rgba(59, 130, 246, 0.3);
  --white: #FFFFFF;
  --muted: #A0A0A0;
  --muted-dim: #666;
  --radius: 12px;
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--white);
  font-size: 19px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

.container { max-width: 960px; margin: 0 auto; padding: 60px 32px; }

/* HEADER */
.page-header { margin-bottom: 56px; }
.class-number {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 3px;
  text-transform: uppercase;
  color: var(--orange);
  margin-bottom: 12px;
}
.page-header h1 {
  font-size: 42px;
  font-weight: 800;
  line-height: 1.15;
  color: var(--white);
  margin-bottom: 16px;
}
.page-header h1 span { color: var(--orange); }
.subtitle {
  font-size: 16px;
  color: var(--muted);
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}
.subtitle .tag {
  background: var(--orange-dim);
  color: var(--orange);
  padding: 4px 12px;
  border-radius: 6px;
  font-weight: 500;
  font-size: 14px;
}

/* SECTIONS */
.section { margin-bottom: 48px; }
.section h2 {
  font-size: 24px;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--orange);
  display: flex;
  align-items: center;
  gap: 10px;
}
.section h2 .icon { color: var(--orange); font-size: 20px; }

/* CARDS */
.card {
  background: var(--card);
  border: 1px solid var(--orange-border);
  border-radius: var(--radius);
  padding: 24px 28px;
  margin-bottom: 16px;
  transition: border-color 0.2s;
}
.card:hover { border-color: var(--orange); }
.card h3 {
  font-size: 18px;
  font-weight: 700;
  color: var(--orange);
  margin-bottom: 16px;
}
.card ul { list-style: none; }
.card li {
  padding: 6px 0;
  padding-left: 20px;
  position: relative;
  font-size: 17px;
  line-height: 1.6;
  color: #E0E0E0;
}
.card li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--orange);
  font-weight: 600;
}

/* STAT BOXES */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 16px;
}
.stat-box {
  background: var(--orange-dim);
  border: 1px solid var(--orange-border);
  border-radius: var(--radius);
  padding: 20px 24px;
  text-align: center;
}
.stat-box .stat-value {
  font-size: 15px;
  font-weight: 600;
  color: var(--orange);
  line-height: 1.5;
}

/* NUMBERED STEPS */
.steps { counter-reset: step; }
.step-item {
  display: flex;
  gap: 20px;
  margin-bottom: 20px;
  align-items: flex-start;
}
.step-num {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  background: var(--orange);
  color: var(--bg);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 16px;
}
.step-text {
  font-size: 17px;
  color: #E0E0E0;
  line-height: 1.6;
  padding-top: 7px;
}

/* BLOCKQUOTE */
blockquote {
  border-left: 4px solid var(--orange);
  padding: 16px 24px;
  margin: 24px 0;
  background: var(--card);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-style: italic;
  color: #E0E0E0;
  font-size: 17px;
}

/* NAVIGATION */
.nav-bottom {
  display: flex;
  justify-content: space-between;
  margin-top: 64px;
  padding-top: 32px;
  border-top: 1px solid #222;
  flex-wrap: wrap;
  gap: 16px;
}
.nav-link {
  color: var(--orange);
  text-decoration: none;
  font-weight: 600;
  font-size: 16px;
  padding: 12px 24px;
  border: 1px solid var(--orange-border);
  border-radius: var(--radius);
  transition: all 0.2s;
}
.nav-link:hover {
  background: var(--orange);
  color: var(--bg);
}

/* INDEX PAGE */
.hero {
  text-align: center;
  margin-bottom: 64px;
  padding: 40px 0;
}
.hero h1 {
  font-size: 52px;
  font-weight: 900;
  margin-bottom: 16px;
}
.hero h1 span { color: var(--orange); }
.hero p { color: var(--muted); font-size: 20px; max-width: 600px; margin: 0 auto; }

.part-header {
  font-size: 28px;
  font-weight: 800;
  margin: 48px 0 24px;
  color: var(--white);
  display: flex;
  align-items: center;
  gap: 12px;
}
.part-header .badge {
  background: var(--orange);
  color: var(--bg);
  font-size: 13px;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 6px;
}

.class-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
  margin-bottom: 32px;
}
.class-card {
  background: var(--card);
  border: 1px solid #222;
  border-radius: var(--radius);
  padding: 0;
  text-decoration: none;
  transition: all 0.25s;
  display: block;
  overflow: hidden;
}
.class-card .card-thumb {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
  display: block;
}
.class-card .card-body {
  padding: 20px 24px 24px;
}
.class-card:hover {
  border-color: var(--orange);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(59, 130, 246, 0.1);
}
.class-card .num {
  font-size: 32px;
  font-weight: 900;
  color: var(--orange);
  margin-bottom: 8px;
}
.class-card .card-title {
  font-size: 17px;
  font-weight: 700;
  color: var(--white);
  margin-bottom: 8px;
  line-height: 1.3;
}
.class-card .card-desc {
  font-size: 14px;
  color: var(--muted);
  line-height: 1.5;
}
.class-card .card-runtime {
  font-size: 13px;
  color: var(--muted-dim);
  margin-top: 12px;
}

/* CLASS HEADER THUMBNAIL */
.class-thumb {
  width: 100%;
  max-width: 480px;
  border-radius: var(--radius);
  border: 1px solid var(--orange-border);
  margin-bottom: 32px;
}

/* SUMMARY BOX */
.summary-box {
  background: var(--card);
  border-left: 4px solid var(--orange);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 24px 28px;
  margin-bottom: 40px;
  font-size: 17px;
  color: #D0D0D0;
  line-height: 1.7;
}

/* TAGS */
.tags { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 8px; }
.tags span {
  background: var(--orange-dim);
  color: var(--orange);
  font-size: 13px;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: 6px;
}

@media (max-width: 640px) {
  .container { padding: 32px 20px; }
  .page-header h1 { font-size: 28px; }
  .hero h1 { font-size: 32px; }
  .stats-grid { grid-template-columns: 1fr; }
  body { font-size: 17px; }
}