:root {
  --bg: #ffffff; --fg: #1f2328; --muted: #59636e; --border: #d1d9e0;
  --link: #0969da; --accent: #0969da; --side-bg: #f6f8fa; --code-bg: #f6f8fa;
  --topbar-bg: #ffffff; --sel: #ddf4ff; --shadow: rgba(31,35,40,.12);
  --hl-keyword: #cf222e; --hl-type: #953800; --hl-string: #0a3069;
  --hl-comment: #59636e; --hl-number: #0550ae; --hl-title: #6639ba;
  --hl-builtin: #0550ae; --hl-meta: #116329; --hl-literal: #0550ae;
}
html[data-theme="dark"] {
  --bg: #0d1117; --fg: #e6edf3; --muted: #9198a1; --border: #2f3742;
  --link: #4493f8; --accent: #4493f8; --side-bg: #0d1117; --code-bg: #161b22;
  --topbar-bg: #0d1117; --sel: #1f3a5f; --shadow: rgba(0,0,0,.5);
  --hl-keyword: #ff7b72; --hl-type: #ffa657; --hl-string: #a5d6ff;
  --hl-comment: #9198a1; --hl-number: #79c0ff; --hl-title: #d2a8ff;
  --hl-builtin: #79c0ff; --hl-meta: #7ee787; --hl-literal: #79c0ff;
}
@media (prefers-color-scheme: dark) {
  html:not([data-theme]) {
    --bg: #0d1117; --fg: #e6edf3; --muted: #9198a1; --border: #2f3742;
    --link: #4493f8; --accent: #4493f8; --side-bg: #0d1117; --code-bg: #161b22;
    --topbar-bg: #0d1117; --sel: #1f3a5f; --shadow: rgba(0,0,0,.5);
    --hl-keyword: #ff7b72; --hl-type: #ffa657; --hl-string: #a5d6ff;
    --hl-comment: #9198a1; --hl-number: #79c0ff; --hl-title: #d2a8ff;
    --hl-builtin: #79c0ff; --hl-meta: #7ee787; --hl-literal: #79c0ff;
  }
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  background: var(--bg); color: var(--fg);
  font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}
::selection { background: var(--sel); }
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* topbar */
.topbar {
  position: fixed; top: 0; left: 0; right: 0; height: 56px; z-index: 30;
  display: flex; align-items: center; gap: 16px; padding: 0 16px;
  background: var(--topbar-bg); border-bottom: 1px solid var(--border);
}
.brand { font-weight: 700; font-size: 17px; color: var(--fg); white-space: nowrap; }
.brand span { color: var(--muted); font-weight: 500; }
.brand:hover { text-decoration: none; }
.home-link {
  display: inline-flex; align-items: center; gap: 6px; white-space: nowrap;
  font-size: 13px; color: var(--muted);
  padding: 5px 9px; border: 1px solid var(--border); border-radius: 6px;
}
.home-link:hover { color: var(--fg); background: var(--side-bg); text-decoration: none; }
.home-link svg { width: 16px; height: 16px; flex-shrink: 0; }
.menu-toggle, .theme-toggle {
  background: none; border: 1px solid transparent; color: var(--fg);
  font-size: 18px; cursor: pointer; padding: 6px 9px; border-radius: 6px; line-height: 1;
}
.menu-toggle:hover, .theme-toggle:hover { background: var(--side-bg); border-color: var(--border); }
.menu-toggle { display: none; }

/* search */
.search { position: relative; margin-left: auto; width: min(340px, 42vw); }
.search-input {
  width: 100%; padding: 7px 12px; border-radius: 8px;
  border: 1px solid var(--border); background: var(--bg); color: var(--fg); font-size: 14px;
}
.search-input:focus { outline: 2px solid var(--accent); outline-offset: -1px; }
.search-results {
  position: absolute; top: 42px; right: 0; width: min(440px, 80vw);
  max-height: 70vh; overflow-y: auto; background: var(--bg);
  border: 1px solid var(--border); border-radius: 10px;
  box-shadow: 0 12px 32px var(--shadow); padding: 6px;
}
.search-hit { display: block; padding: 8px 10px; border-radius: 7px; color: var(--fg); }
.search-hit:hover { background: var(--side-bg); text-decoration: none; }
.search-hit-title { display: block; font-weight: 600; font-size: 14px; }
.search-hit-sub { display: block; font-size: 12px; color: var(--muted); }
.search-empty { padding: 12px; color: var(--muted); font-size: 14px; }

/* layout */
.layout {
  display: grid; grid-template-columns: 290px minmax(0, 1fr) 250px;
  max-width: 1500px; margin: 0 auto; padding-top: 56px;
}
.sidebar, .page-toc {
  position: sticky; top: 56px; align-self: start;
  height: calc(100vh - 56px); overflow-y: auto;
}
.sidebar { border-right: 1px solid var(--border); background: var(--side-bg); }
.sidebar-inner { padding: 20px 14px 60px; }
.sidebar-head, .page-toc-head {
  font-size: 12px; font-weight: 700; text-transform: uppercase;
  letter-spacing: .06em; color: var(--muted); margin-bottom: 10px;
}
.nav-part {
  font-size: 11px; font-weight: 700; text-transform: uppercase;
  letter-spacing: .05em; color: var(--muted); margin: 18px 0 4px; padding: 0 8px;
}
.nav ul { list-style: none; margin: 0; padding: 0; }
.nav-item > a {
  display: block; padding: 5px 8px; border-radius: 6px;
  color: var(--fg); font-size: 14px;
}
.nav-item > a:hover { background: var(--border); text-decoration: none; }
.nav-item.active > a { background: var(--accent); color: #fff; font-weight: 600; }
.nav-sub { margin: 2px 0 6px; border-left: 2px solid var(--border); padding-left: 6px; }
.nav-sub a {
  display: block; padding: 3px 8px; font-size: 13px;
  color: var(--muted); border-radius: 5px;
}
.nav-sub a:hover { color: var(--fg); background: var(--border); text-decoration: none; }

/* content */
.content { min-width: 0; padding: 0 48px 80px; }
.prose { max-width: 760px; margin: 0 auto; padding-top: 28px; }
.prose h1 { font-size: 2.1em; line-height: 1.25; margin: .2em 0 .6em; }
.prose h2 {
  font-size: 1.5em; margin: 1.8em 0 .6em;
  padding-bottom: .3em; border-bottom: 1px solid var(--border);
}
.prose h3 { font-size: 1.2em; margin: 1.5em 0 .5em; }
.prose h4 { font-size: 1.05em; margin: 1.3em 0 .4em; }
.prose h1, .prose h2, .prose h3, .prose h4 { scroll-margin-top: 72px; }
.hanchor {
  margin-left: .35em; color: var(--muted); font-weight: 400;
  opacity: 0; text-decoration: none;
}
h2:hover .hanchor, h3:hover .hanchor, h4:hover .hanchor { opacity: 1; }
.prose img { max-width: 100%; height: auto; display: block; margin: 1.4em auto; }
.prose p { margin: 1em 0; }
.prose ul, .prose ol { padding-left: 1.5em; }
.prose li { margin: .3em 0; }
.prose blockquote {
  margin: 1.2em 0; padding: .4em 1em; color: var(--muted);
  border-left: 3px solid var(--accent); background: var(--side-bg);
}
.prose table {
  display: block; max-width: 100%; overflow-x: auto;
  border-collapse: collapse; margin: 1.2em 0; font-size: 14px;
}
.prose th, .prose td { border: 1px solid var(--border); padding: 6px 12px; }
.prose th { background: var(--side-bg); }
.prose hr { border: none; border-top: 1px solid var(--border); margin: 2em 0; }
.prose code {
  background: var(--code-bg); padding: .15em .4em; border-radius: 5px;
  font-size: .88em; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
.prose pre.code {
  position: relative; background: var(--code-bg); border: 1px solid var(--border);
  border-radius: 10px; padding: 14px 16px; overflow-x: auto; margin: 1.2em 0;
}
.prose pre.code code {
  background: none; padding: 0; font-size: 13.5px; line-height: 1.55;
}
.prose pre.code[data-lang]::before {
  content: attr(data-lang); position: absolute; top: 0; right: 0;
  font-size: 10px; font-weight: 700; letter-spacing: .05em; text-transform: uppercase;
  color: var(--muted); background: var(--border);
  padding: 2px 8px; border-radius: 0 9px 0 9px;
}

/* highlight.js tokens */
.hljs-keyword, .hljs-operator { color: var(--hl-keyword); }
.hljs-type, .hljs-class .hljs-title, .hljs-title.class_ { color: var(--hl-type); }
.hljs-string, .hljs-regexp { color: var(--hl-string); }
.hljs-comment, .hljs-quote { color: var(--hl-comment); font-style: italic; }
.hljs-number, .hljs-literal { color: var(--hl-number); }
.hljs-title, .hljs-title.function_, .hljs-function .hljs-title { color: var(--hl-title); }
.hljs-built_in, .hljs-attr, .hljs-property, .hljs-variable.language_ { color: var(--hl-builtin); }
.hljs-meta, .hljs-attribute, .hljs-symbol { color: var(--hl-meta); }
.hljs-params { color: var(--fg); }
.hljs-section, .hljs-name, .hljs-selector-tag { color: var(--hl-keyword); }
.hljs-emphasis { font-style: italic; }
.hljs-strong { font-weight: 700; }

/* prev / next */
.page-nav {
  max-width: 760px; margin: 48px auto 0; display: flex; gap: 16px;
}
.pnav {
  flex: 1; border: 1px solid var(--border); border-radius: 10px;
  padding: 12px 16px; display: flex; flex-direction: column;
}
.pnav:hover { border-color: var(--accent); text-decoration: none; }
.pnav-next { text-align: right; }
.pnav-dir { font-size: 12px; color: var(--muted); }
.pnav-title { font-weight: 600; color: var(--fg); }
.page-nav > span { flex: 1; }

/* on this page */
.page-toc-inner { padding: 24px 16px 60px; }
.page-toc ul { list-style: none; margin: 0; padding: 0; }
.page-toc li.lvl-3 { padding-left: 12px; }
.page-toc a {
  display: block; padding: 3px 8px; font-size: 13px;
  color: var(--muted); border-left: 2px solid transparent; border-radius: 0 4px 4px 0;
}
.page-toc a:hover { color: var(--fg); text-decoration: none; }
.page-toc a.active {
  color: var(--accent); border-left-color: var(--accent); font-weight: 600;
}

.scrim {
  display: none; position: fixed; inset: 56px 0 0; z-index: 19;
  background: rgba(0,0,0,.45);
}

/* responsive */
@media (max-width: 1180px) {
  .layout { grid-template-columns: 280px minmax(0, 1fr); }
  .page-toc { display: none; }
  .content { padding: 0 32px 80px; }
}
@media (max-width: 820px) {
  .menu-toggle { display: block; }
  .layout { grid-template-columns: minmax(0, 1fr); }
  .sidebar {
    position: fixed; top: 56px; bottom: 0; left: 0; width: 300px; z-index: 20;
    transform: translateX(-100%); transition: transform .2s ease;
  }
  body.nav-open .sidebar { transform: translateX(0); }
  body.nav-open .scrim { display: block; }
  .content { padding: 0 18px 64px; }
}
@media (max-width: 520px) {
  .search { width: 44vw; }
  .brand span { display: none; }
}