:root {
  --bg: #ffffff; --soft: #f5f7f9; --text: #1d232b; --muted: #5f6b7a; --line: #e2e6eb;
  --accent: #157878; --accent-2: #155799; --code: #f0f3f6; --mark: #e3f2f1;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111418; --soft: #181d23; --text: #e6e9ed; --muted: #9aa5b1; --line: #2c333b;
    --accent: #3fb6a8; --accent-2: #6ea8ff; --code: #1f252c; --mark: #17302e;
  }
}
* { box-sizing: border-box; }
html { scroll-padding-top: 72px; }
body { margin: 0; background: var(--bg); color: var(--text); font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; }
a { color: var(--accent); text-underline-offset: 2px; }
.bar { max-width: 1200px; margin: 0 auto; padding: 0 16px; }

.site-header { position: sticky; top: 0; z-index: 10; background: #0f3d55; color: #fff; box-shadow: 0 1px 0 rgba(0,0,0,.15); }
.site-header .bar { display: flex; align-items: center; gap: 16px; height: 56px; overflow-x: auto; }
.brand { color: #fff; font-weight: 700; text-decoration: none; white-space: nowrap; }
.site-nav { display: flex; gap: 2px; margin-left: auto; }
.site-nav a { color: #d6e6ee; text-decoration: none; padding: 6px 11px; border-radius: 6px; font-size: 14.5px; white-space: nowrap; }
.site-nav a:hover { background: rgba(255,255,255,.1); color: #fff; }
.site-nav a.on { background: rgba(255,255,255,.16); color: #fff; }

.hero { background: linear-gradient(120deg, #155799, #159957); color: #fff; padding: 40px 0 32px; }
.hero h1 { margin: 0 0 4px; font-size: 32px; line-height: 1.2; }
.hero p { margin: 0 0 24px; opacity: .9; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 14px; }
.card { display: flex; flex-direction: column; gap: 4px; padding: 16px; border-radius: 12px; background: rgba(255,255,255,.12); border: 1px solid rgba(255,255,255,.25); color: #fff; text-decoration: none; transition: background .15s, transform .15s; }
.card:hover { background: rgba(255,255,255,.2); transform: translateY(-2px); }
.card .ic { font-size: 22px; }
.card b { font-size: 16.5px; }
.card span:last-child { font-size: 14px; opacity: .85; line-height: 1.4; }

.layout { max-width: 1200px; margin: 0 auto; padding: 24px 16px 40px; }
body.has-toc .layout { display: grid; grid-template-columns: 250px minmax(0, 1fr); gap: 40px; }
.page-content { min-width: 0; max-width: 860px; }
body.has-toc .toc { display: block; }
.toc[hidden] { display: none; }
.toc-inner { position: sticky; top: 76px; max-height: calc(100vh - 96px); overflow-y: auto; font-size: 14px; border-left: 2px solid var(--line); padding-left: 14px; }
.toc-title { display: block; background: none; border: 0; padding: 0; cursor: default; font-family: inherit; font-weight: 650; color: var(--muted); font-size: 12px; text-transform: uppercase; letter-spacing: .06em; margin-bottom: 6px; }
.toc a { display: block; color: var(--muted); text-decoration: none; padding: 3px 0; line-height: 1.35; }
.toc a.h3 { padding-left: 12px; font-size: 13px; }
.toc a:hover, .toc a.on { color: var(--accent); }
.toc a.on { font-weight: 600; }

.page-content h1 { font-size: 30px; line-height: 1.25; margin: 0 0 16px; }
.page-content h2 { font-size: 23px; line-height: 1.3; margin: 40px 0 12px; padding-bottom: 6px; border-bottom: 1px solid var(--line); }
.page-content h3 { font-size: 18px; margin: 28px 0 10px; }
.page-content h1 + h2, .page-content > h2:first-child { margin-top: 8px; }
.page-content blockquote { margin: 16px 0; padding: 10px 16px; border-left: 4px solid var(--accent); background: var(--soft); color: var(--muted); border-radius: 0 8px 8px 0; }
.page-content blockquote p { margin: 0; }
.page-content code { background: var(--code); padding: 1px 5px; border-radius: 4px; font-size: .9em; }
.page-content pre { background: var(--code); padding: 14px; border-radius: 8px; overflow-x: auto; font-size: 14px; line-height: 1.5; }
.page-content pre code { background: none; padding: 0; }
.page-content ul, .page-content ol { padding-left: 24px; }
.page-content li + li { margin-top: 4px; }
.page-content hr { border: 0; border-top: 1px solid var(--line); margin: 32px 0; }
.table-wrap { overflow-x: auto; margin: 14px 0 20px; border: 1px solid var(--line); border-radius: 10px; }
.page-content table { border-collapse: collapse; width: 100%; font-size: 14.5px; line-height: 1.5; }
.page-content th, .page-content td { padding: 8px 12px; border-top: 1px solid var(--line); vertical-align: top; }
.page-content th { background: var(--soft); text-align: left; font-weight: 650; border-top: 0; white-space: nowrap; }
.page-content tbody tr:hover td { background: var(--soft); }
.page-content .task-list-item { list-style: none; margin-left: -20px; }
body.home .page-content > h1:first-child { display: none; }
body.home .page-content > p:first-of-type { margin-top: 0; }
a.book-link::after { content: " 📖"; font-size: .85em; }

.site-footer { border-top: 1px solid var(--line); color: var(--muted); font-size: 13.5px; text-align: center; padding: 20px 16px 32px; }

@media (max-width: 1000px) {
  body.has-toc .layout { display: block; }
  .toc-inner { position: static; max-height: none; border: 1px solid var(--line); border-radius: 10px; padding: 12px 14px; margin-bottom: 8px; }
  .toc-title { cursor: pointer; margin: 0; width: 100%; text-align: left; }
  .toc-title::after { content: " ▾"; }
  .toc.open .toc-title::after { content: " ▴"; }
  .toc nav { display: none; max-height: 300px; overflow-y: auto; margin-top: 8px; }
  .toc.open nav { display: block; }
}
@media (max-width: 600px) {
  .hero { padding: 28px 0 24px; }
  .hero h1 { font-size: 25px; }
  .page-content h1 { font-size: 25px; }
  .brand { display: none; }
  .site-nav { margin-left: 0; }
}