:root {
  color-scheme: dark;
  --bg: #111113;
  --surface: #1a1a1e;
  --fg: #eeeeF0;
  --muted: #a0a0a9;
  --border: #303034;
  --accent: #85bdff;
  --active: #222e3d;
}
* { box-sizing: border-box; }
html { scroll-padding-top: 100px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-underline-offset: .2em; }
a:hover { text-decoration-thickness: 2px; }
a:focus-visible, summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 5px; }
.skip-link { position: fixed; top: -80px; left: 20px; z-index: 5; padding: 12px; background: var(--bg); }
.skip-link:focus { top: 10px; }
.site-header {
  height: 76px;
  padding: 0 max(28px, calc((100vw - 1440px) / 2));
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 2;
}
.site-header a { color: var(--fg); text-decoration: none; font-size: 13px; }
.site-header .brand { font-size: 23px; font-weight: 650; letter-spacing: -.6px; }
.brand span { color: var(--muted); font-size: 16px; font-weight: 400; letter-spacing: 0; }
.manual-shell { display: grid; grid-template-columns: 256px minmax(0, 1fr); max-width: 1440px; margin: 0 auto; }
.sidebar { padding: 34px 24px 30px 28px; border-right: 1px solid var(--border); }
.sidebar nav { position: sticky; top: 108px; max-height: calc(100vh - 136px); overflow-y: auto; scrollbar-width: thin; }
.nav-label { color: var(--muted); font-size: 11px; text-transform: uppercase; letter-spacing: .1em; margin: 0 10px 16px; }
.chapter-list { list-style: none; padding: 0; margin: 0; }
.chapter-list a { display: block; padding: 8px 10px; border-radius: 5px; color: var(--muted); text-decoration: none; font-size: 13px; line-height: 1.4; }
.chapter-list a:hover { background: var(--surface); color: var(--fg); }
.chapter-list a[aria-current] { color: var(--accent); background: var(--active); }
.reading-pane { min-width: 0; padding: 48px clamp(28px, 4vw, 64px) 24px; }
main { max-width: 980px; margin: 0 auto; font-size: 16px; line-height: 1.8; overflow-wrap: break-word; }
.eyebrow { color: var(--muted); font-size: 11px; text-transform: uppercase; letter-spacing: .12em; margin: 0 0 10px; }
h1, h2, h3 { line-height: 1.2; font-weight: 560; }
h1 { font-size: clamp(32px, 3.5vw, 48px); letter-spacing: -1.6px; margin: 0 0 28px; }
h2 { font-size: 25px; letter-spacing: -.5px; margin: 48px 0 18px; }
h3 { font-size: 19px; margin: 30px 0 12px; }
p { margin: 16px 0; }
main > p, main > ol, main > ul:not(.chapter-menu) { max-width: 76ch; }
main > h1 + p { color: var(--muted); font-size: 18px; line-height: 1.7; }
main ul, main ol { padding-left: 24px; }
main li { padding-left: 4px; margin: 6px 0; }
strong { font-weight: 650; }
code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .86em; background: var(--surface); padding: .15em .35em; border-radius: 4px; }
pre { padding: 18px 22px; overflow-x: auto; border: 1px solid var(--border); border-radius: 8px; background: var(--surface); line-height: 1.65; }
pre code { padding: 0; }
.app-action { font-weight: 500; }
figure { margin: 28px 0 32px; }
figure img { display: block; max-width: 100%; height: auto; border: 1px solid var(--border); border-radius: 8px; background: #1a1a1e; }
figcaption { color: var(--muted); font-size: 13px; line-height: 1.6; margin-top: 12px; max-width: 80ch; }
main .chapter-menu { list-style: none; padding: 0; margin: 32px 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); column-gap: 32px; }
.chapter-menu li { border-top: 1px solid var(--border); padding: 20px 0; margin: 0; }
.chapter-menu a { color: var(--fg); font-size: 17px; font-weight: 550; text-decoration: none; }
.chapter-menu a:hover { color: var(--accent); }
.chapter-menu p { margin: 6px 0 0; font-size: 13px; line-height: 1.65; color: var(--muted); }
.page-turn { max-width: 980px; margin: 52px auto 0; padding-top: 24px; border-top: 1px solid var(--border); display: flex; justify-content: space-between; gap: 24px; }
.page-turn a { text-decoration: none; font-size: 15px; line-height: 1.6; }
.page-turn a[rel=next] { margin-left: auto; text-align: right; }
.page-turn span { display: block; color: var(--muted); font-size: 12px; margin-bottom: 5px; }
footer { max-width: 980px; margin: 36px auto 0; padding-top: 18px; color: var(--muted); font-size: 12px; }
footer span { margin: 0 8px; }
footer a { color: var(--muted); }
.mobile-chapters { display: none; }
@media (max-width: 760px) {
  .site-header { height: 64px; padding: 0 20px; }
  .manual-shell { display: block; }
  .sidebar { display: none; }
  .reading-pane { padding: 20px 20px 28px; }
  .mobile-chapters { display: block; border-bottom: 1px solid var(--border); margin: 0 0 32px; padding-bottom: 16px; }
  .mobile-chapters summary { cursor: pointer; color: var(--muted); font-size: 14px; }
  .mobile-chapters nav { margin-top: 16px; }
  .chapter-list a { padding: 10px; font-size: 14px; }
  main { font-size: 16px; line-height: 1.75; }
  h1 { letter-spacing: -1px; }
  h2 { font-size: 23px; margin-top: 38px; }
  main .chapter-menu { grid-template-columns: 1fr; }
  .page-turn { gap: 16px; }
}
@media print {
  :root { color-scheme: light; --bg: white; --fg: black; --muted: #444; --border: #ccc; --accent: black; }
  .site-header, .sidebar, .mobile-chapters, .page-turn, footer, .eyebrow { display: none; }
  .manual-shell { display: block; }
  .reading-pane { padding: 0; }
  main { max-width: none; font-size: 11pt; }
  h1 { font-size: 26pt; }
  h2, h3 { break-after: avoid; }
  figure, pre { break-inside: avoid; }
}