:root { --bg:#070A0F; --surface:#10161F; --border:#223040; --text:#E8EEF5;
  --muted:#8FA3B8; --off:#3E4C5E; --mark:#F2F7FC; --loss:#F87171;
  --F:#7C8DA6; --R:#38BDF8; --L:#A78BFA;
  --K:#FB923C; --S:#F472B6; --Y:#34D399; }
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text);
  font: 17px/1.65 Inter, 'Segoe UI', system-ui, -apple-system, Arial, Helvetica, sans-serif;
  font-feature-settings: "tnum"; }
a { color: var(--text); text-decoration-color: var(--off); text-underline-offset: 3px; }
a:hover { text-decoration-color: var(--text); }
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 20px; }
.prose { max-width: 720px; }
header.site { border-bottom: 1px solid var(--border); }
header.site .wrap { display: flex; align-items: center; gap: 28px; height: 68px; }
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; font-weight: 700;
  letter-spacing: .02em; }
nav.top { display: flex; gap: 22px; margin-left: auto; font-size: 15px; }
nav.top a { text-decoration: none; color: var(--muted); }
nav.top a:hover, nav.top a[aria-current] { color: var(--text); }
.yt { border: 1px solid var(--border); border-radius: 8px; padding: 6px 12px; }
.label { text-transform: uppercase; letter-spacing: .18em; font-size: 12px; color: var(--muted);
  font-weight: 600; }
h1 { font-size: clamp(34px, 6vw, 56px); line-height: 1.08; margin: 18px 0 18px;
  letter-spacing: -.02em; }
h2 { font-size: 26px; line-height: 1.2; margin: 56px 0 16px; letter-spacing: -.01em; }
h3 { font-size: 19px; margin: 28px 0 8px; }
.lead { font-size: 20px; color: var(--text); max-width: 760px; }
.muted { color: var(--muted); }
section { padding: 8px 0 8px; }
.hero { padding: 64px 0 24px; }
.cta { display: flex; flex-wrap: wrap; gap: 12px; margin: 28px 0 8px; }
.btn { display: inline-block; padding: 12px 18px; border-radius: 10px; text-decoration: none;
  font-weight: 600; border: 1px solid var(--border); }
.btn.primary { background: var(--text); color: var(--bg); border-color: var(--text); }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px;
  margin: 40px 0 8px; }
.stat { background: var(--surface); border: 1px solid var(--border); border-radius: 12px;
  padding: 16px 18px; }
.stat b { display: block; font-size: 30px; letter-spacing: -.01em; }
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 14px; }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: 14px;
  padding: 20px 22px; }
.card h3 { margin-top: 10px; }
.card p { margin: 6px 0 0; color: var(--muted); font-size: 15.5px; }
a.card { text-decoration: none; display: block; }
a.card:hover { border-color: var(--off); }
.ticks { display: inline-flex; align-items: flex-end; gap: 3px; vertical-align: middle; }
.ticks i { display: block; width: 6px; height: 10px; border-radius: 2px; background: var(--off); }
.ticks i.on { width: 9px; height: 16px; }
ol.claims { counter-reset: c; list-style: none; padding: 0; margin: 0; }
ol.claims li { counter-increment: c; position: relative; padding: 14px 0 14px 52px;
  border-top: 1px solid var(--border); }
ol.claims li::before { content: counter(c); position: absolute; left: 0; top: 12px;
  font-size: 22px; font-weight: 700; color: var(--muted); }
.module-head { display: flex; align-items: center; gap: 12px; margin-top: 56px; }
.module-head h2 { margin: 0; }
ul.lessons { list-style: none; padding: 0; margin: 14px 0 0; }
ul.lessons li { border-top: 1px solid var(--border); }
ul.lessons a { display: grid; grid-template-columns: 168px 1fr; gap: 18px; padding: 16px 0;
  text-decoration: none; }
ul.lessons img { width: 168px; height: auto; border-radius: 8px; border: 1px solid var(--border); }
ul.lessons .t { font-weight: 600; font-size: 18px; }
ul.lessons .s { color: var(--muted); font-size: 15px; margin-top: 4px; }
.meta { display: flex; flex-wrap: wrap; gap: 8px 18px; color: var(--muted); font-size: 14.5px; }
.badge { font-size: 12px; letter-spacing: .12em; text-transform: uppercase; color: var(--muted);
  border: 1px solid var(--border); border-radius: 6px; padding: 1px 7px; }
.video { position: relative; display: block; border-radius: 14px; overflow: hidden;
  border: 1px solid var(--border); margin: 28px 0 8px; }
.video img { display: block; width: 100%; height: auto; }
.video .over { display: block; padding: 12px 18px; background: var(--surface);
  border-top: 1px solid var(--border); font-weight: 600; }
.box { background: var(--surface); border: 1px solid var(--border); border-radius: 14px;
  padding: 18px 22px; margin: 22px 0; }
.box h2 { margin: 0 0 8px; font-size: 20px; }
ol.chapters { list-style: none; padding: 0; margin: 0; columns: 2 280px; column-gap: 32px; }
ol.chapters li { break-inside: avoid; padding: 4px 0; }
ol.chapters .ts { display: inline-block; min-width: 54px; color: var(--muted); }
details { border-top: 1px solid var(--border); padding: 14px 0; }
summary { cursor: pointer; font-weight: 600; }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin: 40px 0; }
.pager a { text-decoration: none; }
.pager .next { text-align: right; }
code, pre { font-family: Consolas, 'SF Mono', Menlo, monospace; font-size: 14.5px; }
pre { background: var(--surface); border: 1px solid var(--border); border-radius: 10px;
  padding: 14px 16px; overflow-x: auto; }
table { border-collapse: collapse; width: 100%; font-size: 15px; }
td, th { text-align: left; padding: 8px 10px 8px 0; border-top: 1px solid var(--border);
  vertical-align: top; }
footer.site { border-top: 1px solid var(--border); margin-top: 72px; padding: 36px 0 48px;
  color: var(--muted); font-size: 14.5px; }
footer.site .cols { display: flex; flex-wrap: wrap; gap: 18px 40px; justify-content: space-between; }
footer.site nav { display: flex; flex-wrap: wrap; gap: 8px 20px; }
footer.site a { color: var(--muted); }
@media (max-width: 720px) {
  header.site .wrap { height: auto; flex-wrap: wrap; padding-top: 14px; padding-bottom: 14px;
    gap: 12px 20px; }
  nav.top { margin-left: 0; width: 100%; gap: 8px 18px; flex-wrap: wrap; }
  nav.top .yt { display: none; }
  ul.lessons a { grid-template-columns: 112px 1fr; gap: 12px; }
  ul.lessons img { width: 112px; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { text-align: left; }
  body { font-size: 16.5px; }
}