:root {
  --ink: #f3f5f7;
  --muted: #a0a0a0;
  --line: #3c3f41;
  --paper: #111621;
  --surface: #303234;
  --surface-raised: #3c3f41;
  --blue: #29b6f6;
  --blue-dark: #2196f3;
  --cyan: #00bcd4;
  --blue-soft: rgba(41, 182, 246, .14);
  --shadow: 0 18px 42px rgba(0, 0, 0, .28);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; color: var(--ink); background: var(--paper); font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; }
a { color: inherit; }

.topbar { width: min(1180px, calc(100% - 40px)); height: 76px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; border-bottom: 1px solid var(--line); }
.brand { display: inline-flex; align-items: center; gap: 12px; text-decoration: none; }
.brand-logo { display: block; width: auto; height: 32px; }
.docs-label { padding-left: 12px; border-left: 1px solid #515151; color: #cccccc; font-size: 15px; font-weight: 700; letter-spacing: -.01em; }
.app-link, .playlist-link { color: var(--blue); font-size: 14px; font-weight: 700; text-decoration: none; }
.app-link:hover, .playlist-link:hover { text-decoration: underline; }

main { width: min(1180px, calc(100% - 40px)); margin: 0 auto; }
.hero { padding: 112px 0 104px; max-width: 820px; }
.eyebrow { margin: 0 0 12px; color: var(--blue); font-size: 12px; font-weight: 800; letter-spacing: .13em; text-transform: uppercase; }
h1, h2, p { margin-top: 0; }
h1 { margin-bottom: 24px; max-width: 800px; font-size: clamp(42px, 7vw, 76px); line-height: .98; letter-spacing: -.055em; }
h2 { margin-bottom: 0; font-size: clamp(28px, 4vw, 42px); line-height: 1.05; letter-spacing: -.035em; }
.hero-copy, .page-intro > p:not(.eyebrow) { max-width: 660px; color: var(--muted); font-size: 19px; line-height: 1.65; }

.section, .video-section { padding: 76px 0; border-top: 1px solid var(--line); }
.section-heading { display: flex; align-items: end; justify-content: space-between; gap: 32px; margin-bottom: 34px; }
.section-heading > p { max-width: 360px; margin-bottom: 3px; color: var(--muted); line-height: 1.55; }
.topic-grid { display: grid; gap: 16px; grid-template-columns: repeat(3, 1fr); }
.topic-card { min-height: 230px; padding: 26px; display: flex; flex-direction: column; gap: 25px; border: 1px solid var(--line); border-radius: 18px; background: var(--surface); text-decoration: none; transition: transform .2s ease, box-shadow .2s ease, border-color .2s ease; }
.topic-card--active:hover { transform: translateY(-4px); border-color: var(--blue); box-shadow: var(--shadow); }
.topic-card > span:nth-child(2) { display: grid; gap: 9px; }
.topic-card strong { font-size: 21px; letter-spacing: -.02em; }
.topic-card small { color: var(--muted); font-size: 14px; line-height: 1.55; }
.topic-icon { display: grid; place-items: center; width: 42px; height: 42px; border-radius: 12px; color: var(--blue); background: var(--blue-soft); font-weight: 900; }
.arrow { margin-top: auto; color: var(--cyan); font-size: 24px; }
.soon-badge { width: max-content; margin-top: auto; padding: 6px 10px; border-radius: 999px; color: var(--muted); background: var(--surface-raised); font-size: 11px; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; }

.breadcrumbs { padding-top: 40px; display: flex; gap: 9px; color: var(--muted); font-size: 13px; }
.breadcrumbs a { color: var(--blue); font-weight: 700; text-decoration: none; }
.page-intro { padding: 76px 0 82px; }
.page-intro h1 { margin-bottom: 20px; }
.playlist-link { display: inline-block; margin-top: 14px; }

.video-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.video-card { overflow: hidden; border: 1px solid var(--line); border-radius: 16px; background: var(--surface); text-decoration: none; transition: transform .2s ease, box-shadow .2s ease, border-color .2s ease; }
.video-card:hover { transform: translateY(-4px); border-color: var(--blue); box-shadow: var(--shadow); }
.thumbnail { position: relative; display: block; overflow: hidden; aspect-ratio: 16 / 9; background: #20242c; }
.thumbnail img { width: 100%; height: 100%; display: block; object-fit: cover; transition: transform .25s ease; }
.video-card:hover img { transform: scale(1.025); }
.play { position: absolute; inset: 50% auto auto 50%; display: grid; place-items: center; width: 46px; height: 46px; padding-left: 3px; transform: translate(-50%, -50%); border-radius: 50%; color: white; background: rgba(33, 150, 243, .94); box-shadow: 0 8px 20px rgba(0,0,0,.3); }
.duration { position: absolute; right: 9px; bottom: 9px; padding: 4px 7px; border-radius: 5px; color: white; background: rgba(10, 20, 14, .85); font-size: 11px; font-weight: 800; }
.video-meta { min-height: 154px; padding: 21px; display: flex; flex-direction: column; }
.video-meta small { margin-bottom: 8px; color: var(--blue); font-size: 11px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.video-meta strong { font-size: 18px; line-height: 1.35; letter-spacing: -.015em; }
.video-meta span { margin-top: auto; padding-top: 20px; color: var(--muted); font-size: 12px; font-weight: 700; }

footer { width: min(1180px, calc(100% - 40px)); margin: 40px auto 0; padding: 28px 0 46px; display: flex; justify-content: space-between; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }

a:focus-visible { outline: 3px solid var(--cyan); outline-offset: 4px; border-radius: 4px; }

@media (max-width: 900px) {
  .topic-grid, .video-grid { grid-template-columns: repeat(2, 1fr); }
  .section-heading { align-items: start; flex-direction: column; }
}

@media (max-width: 620px) {
  .topbar, main, footer { width: min(100% - 28px, 1180px); }
  .topbar { height: 66px; }
  .brand-logo { height: 26px; }
  .docs-label { padding-left: 9px; font-size: 13px; }
  .app-link { font-size: 12px; }
  .hero { padding: 76px 0 72px; }
  .page-intro { padding: 54px 0 62px; }
  .section, .video-section { padding: 56px 0; }
  .topic-grid, .video-grid { grid-template-columns: 1fr; }
  .topic-card { min-height: 205px; }
  footer { gap: 12px; flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; }
}