:root {
  color-scheme: light;
  --bg: #fff; --panel: #f6f6f7; --text: #23232a; --muted: #555562;
  --line: #dedee3; --accent: #6633cc; --accent-soft: #eee7fc;
  --code: #f6f6f8; --note: #f0ebfb; --warning: #fff5da; --warning-text: #62440a;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg: #18181b; --panel: #202024; --text: #ededf0; --muted: #b6b6c2;
    --line: #35353e; --accent: #b7a0ff; --accent-soft: #342452;
    --code: #24242b; --note: #28223c; --warning: #342b18; --warning-text: #f7d992;
  }
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #18181b; --panel: #202024; --text: #ededf0; --muted: #b6b6c2;
  --line: #35353e; --accent: #b7a0ff; --accent-soft: #342452;
  --code: #24242b; --note: #28223c; --warning: #342b18; --warning-text: #f7d992;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-padding-top: 88px; }
body { margin: 0; background: var(--bg); color: var(--text); font-size: 16px; line-height: 1.8; }
a { color: var(--accent); text-underline-offset: 3px; }
button, input, select { font: inherit; }
button, summary, select { cursor: pointer; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 4px; }
.skip-link { position: fixed; top: -90px; left: 16px; z-index: 10; background: var(--bg); padding: 8px 16px; }
.skip-link:focus { top: 8px; }
.topbar { height: 64px; position: sticky; top: 0; z-index: 5; background: var(--panel); border-bottom: 1px solid var(--line); display: flex; align-items: center; gap: 24px; padding: 0 24px; }
.brand { font-size: 21px; font-weight: 650; text-decoration: none; white-space: nowrap; letter-spacing: -.7px; }
.search { max-width: 340px; flex: 1; position: relative; margin-left: 24px; }
.search input { width: 100%; height: 38px; padding: 0 12px; background: var(--bg); color: var(--text); border: 1px solid var(--line); border-radius: 7px; font-size: 13px; }
.search-results { position: absolute; top: 44px; left: 0; right: 0; background: var(--bg); border: 1px solid var(--line); border-radius: 7px; padding: 8px; box-shadow: 0 8px 24px #0002; max-height: 340px; overflow: auto; }
.search-results a { display: block; padding: 7px; font-size: 13px; }
.search-results p { padding: 4px 8px; font-size: 13px; margin: 0; }
.top-actions { margin-left: auto; display: flex; gap: 16px; align-items: center; font-size: 13px; }
.repo-link { color: var(--text); display: flex; align-items: center; }
.repo-link svg { width: 21px; height: 21px; }
.theme-label { display: flex; gap: 7px; align-items: center; border-left: 1px solid var(--line); padding-left: 16px; }
.theme-label select { background: transparent; border: 0; color: var(--text); padding: 8px 2px; font-size: 13px; }
.language { border-left: 1px solid var(--line); padding-left: 16px; white-space: nowrap; }
.layout { display: grid; grid-template-columns: 280px minmax(0, 1fr) 225px; min-height: calc(100dvh - 64px); max-width: 1700px; margin: auto; }
.sidebar { background: var(--panel); border-right: 1px solid var(--line); padding: 28px 24px; position: sticky; top: 64px; height: calc(100dvh - 64px); overflow: auto; }
.sidebar nav > a { display: block; margin-bottom: 18px; font-weight: 600; }
.sidebar a { color: var(--muted); text-decoration: none; font-size: 13px; line-height: 1.5; padding: 7px 10px; border-radius: 4px; }
.sidebar a:hover { color: var(--text); background: var(--accent-soft); }
.sidebar a[aria-current="page"] { background: var(--accent-soft); color: var(--accent); font-weight: 650; }
.sidebar details { margin-bottom: 18px; }
.sidebar summary { font-size: 14px; font-weight: 650; margin-bottom: 8px; }
.lesson-links { display: grid; border-left: 1px solid var(--line); margin-left: 5px; padding-left: 9px; }
.sidebar-note { border-top: 1px solid var(--line); margin-top: 22px; padding-top: 16px; color: var(--muted); font-size: 12px; }
.sidebar-note strong { color: var(--text); }
.mobile-menu { display: none; background: var(--panel); border-bottom: 1px solid var(--line); padding: 10px 20px; }
.mobile-menu summary { font-size: 14px; }
.mobile-menu nav { display: grid; gap: 8px; padding: 15px 0; }
.mobile-menu a { font-size: 13px; }
main { min-width: 0; padding: 38px 48px 0; max-width: 960px; width: 100%; margin: 0 auto; }
.breadcrumbs { font-size: 12px; color: var(--muted); margin: 0 0 25px; display: flex; flex-wrap: wrap; gap: 8px; }
.breadcrumbs a { color: var(--muted); }
.eyebrow { color: var(--muted); font-size: 12px; margin-bottom: 12px; }
h1 { font-size: clamp(30px, 3.1vw, 43px); line-height: 1.2; letter-spacing: -1.1px; margin: 0 0 27px; font-weight: 700; }
h2 { font-size: 25px; line-height: 1.35; letter-spacing: -.5px; margin: 36px 0 15px; }
h3 { font-size: 19px; margin: 27px 0 12px; }
p { margin: 16px 0; }
.lead { font-size: 17px; color: var(--muted); }
li { margin: 9px 0; padding-left: 3px; }
ul, ol { padding-left: 25px; }
code, kbd { font: .86em/1.65 ui-monospace, SFMono-Regular, Consolas, monospace; border-radius: 4px; background: var(--code); padding: 2px 5px; overflow-wrap: anywhere; }
kbd { border: 1px solid var(--line); white-space: nowrap; }
.callout { background: var(--note); border-left: 3px solid var(--accent); padding: 15px 20px; margin: 24px 0; font-size: 14px; }
.callout strong:first-child { display: block; }
.callout p { margin: 6px 0 0; }
.callout.warning { background: var(--warning); border-color: var(--warning-text); color: var(--warning-text); }
.track-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin: 26px 0; }
.track-card { display: block; color: var(--text); text-decoration: none; border: 1px solid var(--line); padding: 23px; border-radius: 8px; }
.track-card:hover { border-color: var(--accent); }
.track-card strong { font-size: 20px; display: block; line-height: 1.3; }
.track-card span { display: block; color: var(--muted); font-size: 14px; margin-top: 12px; }
.track-card small { color: var(--accent); display: block; margin-top: 16px; font-size: 13px; }
.prompt { border: 1px solid var(--line); background: var(--code); border-radius: 7px; overflow: hidden; margin: 22px 0; }
.prompt-header { display: flex; justify-content: space-between; align-items: center; gap: 12px; border-bottom: 1px solid var(--line); padding: 8px 15px; color: var(--muted); font-size: 11px; }
.copy-button { border: 1px solid var(--line); background: var(--bg); color: var(--text); border-radius: 4px; padding: 7px 11px; font-size: 12px; min-height: 36px; }
pre { white-space: pre-wrap; overflow-wrap: anywhere; font: 13px/1.85 ui-monospace, SFMono-Regular, Consolas, monospace; padding: 18px; margin: 0; }
pre code { font: inherit; padding: 0; background: none; }
figure { margin: 26px 0; }
.screenshot { position: relative; background: #10141b; border: 1px solid var(--line); border-radius: 7px; overflow: hidden; }
.screenshot img { display: block; width: 100%; height: auto; }
.screenshot a { display: block; }
.pin { position: absolute; width: 25px; height: 25px; display: grid; place-items: center; border-radius: 50%; background: #ffe066; color: #151515; border: 2px solid #151515; font-size: 12px; font-weight: 800; transform: translate(-50%, -50%); pointer-events: none; box-shadow: 0 0 0 2px #fff; }
figcaption { margin-top: 10px; color: var(--muted); font-size: 12px; line-height: 1.65; }
.image-key { background: var(--panel); border: 1px solid var(--line); border-radius: 6px; padding: 11px 17px 11px 36px; font-size: 14px; }
.image-key li::marker { color: var(--accent); font-weight: 750; }
.table-scroll { overflow: auto; border: 1px solid var(--line); border-radius: 6px; margin: 22px 0; }
table { width: 100%; min-width: 440px; border-collapse: collapse; font-size: 13px; line-height: 1.7; }
td, th { border-bottom: 1px solid var(--line); padding: 11px 14px; text-align: left; vertical-align: top; }
th { background: var(--panel); }
tr:last-child td { border-bottom: 0; }
details.help { border: 1px solid var(--line); padding: 13px 17px; margin: 20px 0; border-radius: 6px; font-size: 14px; }
details.help summary { font-weight: 600; }
.checkpoint { margin-top: 30px; display: flex; gap: 12px; padding: 16px 18px; border: 1px solid var(--line); border-radius: 6px; font-size: 14px; cursor: pointer; }
.checkpoint input { flex-shrink: 0; width: 18px; height: 18px; margin-top: 4px; accent-color: var(--accent); }
.checkpoint strong { display: block; color: var(--accent); font-size: 12px; }
.on-this-page { position: sticky; top: 64px; align-self: start; height: calc(100dvh - 64px); overflow: auto; padding: 37px 22px 20px; border-left: 1px solid var(--line); }
.on-this-page h2 { font-size: 14px; margin: 0 0 16px; letter-spacing: 0; }
.on-this-page nav { display: grid; gap: 10px; }
.on-this-page a { color: var(--muted); text-decoration: none; font-size: 12px; line-height: 1.5; }
.on-this-page a:hover { color: var(--accent); }
.page-navigation { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 40px 0 26px; }
.page-navigation a { border: 1px solid var(--line); padding: 13px 18px; border-radius: 7px; color: var(--text); text-decoration: none; font-size: 14px; }
.page-navigation a:last-child { text-align: right; grid-column: 2; }
.page-navigation small { display: block; color: var(--muted); font-size: 11px; }
.page-navigation a:hover { border-color: var(--accent); }
footer { border-top: 1px solid var(--line); color: var(--muted); font-size: 11px; margin-top: 30px; padding: 21px 0 30px; }
.sources { font-size: 13px; color: var(--muted); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
@media (max-width: 1200px) {
  .layout { grid-template-columns: 250px minmax(0, 1fr); }
  .on-this-page { display: none; }
  main { padding-inline: 38px; }
}
@media (max-width: 800px) {
  .layout { display: block; }
  .sidebar { display: none; }
  .mobile-menu { display: block; }
  .topbar { padding-inline: 20px; gap: 12px; }
  .brand { font-size: 18px; }
  .search { margin-left: 0; max-width: none; }
  .language, .repo-link { display: none; }
  .theme-label { border: 0; padding: 0; }
  main { padding: 26px 24px 0; }
}
@media (max-width: 530px) {
  .topbar { flex-wrap: wrap; height: auto; min-height: 64px; padding-block: 10px; gap: 8px; }
  .search { order: 3; flex-basis: 100%; }
  .track-grid { grid-template-columns: 1fr; }
  .top-actions { gap: 8px; }
  h1 { font-size: 31px; }
  main { padding-inline: 20px; }
  .page-navigation { gap: 10px; }
  .page-navigation a { padding: 11px; font-size: 12px; }
  .pin { width: 21px; height: 21px; font-size: 10px; }
  html { scroll-padding-top: 125px; }
}
@media print {
  :root, :root[data-theme], :root:not([data-theme]) { color-scheme: light; --bg: #fff; --panel: #eee; --text: #000; --muted: #333; --line: #aaa; --accent: #442299; --accent-soft: #eee; --code: #eee; --note: #eee; --warning: #eee; --warning-text: #222; }
  .topbar, .sidebar, .mobile-menu, .on-this-page, .page-navigation, .copy-button, .checkpoint { display: none; }
  .layout { display: block; }
  main { max-width: none; padding: 0; }
  .lesson[hidden] { display: block !important; }
  .lesson { break-before: page; }
  .lesson:first-child { break-before: auto; }
  .prompt, figure { break-inside: avoid; }
  details.help > * { display: block; }
  h1, h2, h3 { break-after: avoid; }
}