:root {
  --bg: #ffffff;
  --bg-soft: #f6f7f9;
  --bg-code: #f3f4f6;
  --fg: #1c2330;
  --fg-soft: #5b6475;
  --line: #e3e6ec;
  --accent: #2456d6;
  --accent-soft: #e8eefc;
  --tip: #0f7b4f;
  --tip-bg: #e7f6ef;
  --note: #2456d6;
  --note-bg: #e8eefc;
  --warn: #a15c00;
  --warn-bg: #fff3dc;
  --exp: #6b3fb0;
  --exp-bg: #f1eafb;
  --sidebar-w: 300px;
  --header-h: 56px;
  --font: "Pretendard", "Noto Sans KR", "Apple SD Gothic Neo", "Malgun Gothic", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", "D2Coding", Consolas, Menlo, monospace;
}
:root[data-theme="dark"] {
  --bg: #12161d;
  --bg-soft: #1a2029;
  --bg-code: #1b212b;
  --fg: #e4e8ee;
  --fg-soft: #9aa5b6;
  --line: #2a3240;
  --accent: #7ba2ff;
  --accent-soft: #1d2a4a;
  --tip: #5fd6a2;
  --tip-bg: #14291f;
  --note: #7ba2ff;
  --note-bg: #1a2744;
  --warn: #f0b45a;
  --warn-bg: #30250f;
  --exp: #c3a2f5;
  --exp-bg: #261c3a;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #12161d; --bg-soft: #1a2029; --bg-code: #1b212b; --fg: #e4e8ee; --fg-soft: #9aa5b6; --line: #2a3240;
    --accent: #7ba2ff; --accent-soft: #1d2a4a; --tip: #5fd6a2; --tip-bg: #14291f; --note: #7ba2ff; --note-bg: #1a2744;
    --warn: #f0b45a; --warn-bg: #30250f; --exp: #c3a2f5; --exp-bg: #261c3a;
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-h) + 16px); }
body { margin: 0; background: var(--bg); color: var(--fg); font: 16px/1.75 var(--font); -webkit-text-size-adjust: 100%; word-break: keep-all; overflow-wrap: break-word; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
.skip-link { position: absolute; left: -999px; top: 0; background: var(--accent); color: #fff; padding: 8px 12px; z-index: 100; }
.skip-link:focus { left: 8px; top: 8px; }

/* header */
.site-header { position: sticky; top: 0; z-index: 50; height: var(--header-h); background: var(--bg); border-bottom: 1px solid var(--line); }
.header-inner { height: 100%; max-width: 1480px; margin: 0 auto; padding: 0 16px; display: flex; align-items: center; gap: 12px; }
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--fg); white-space: nowrap; }
.brand:hover { text-decoration: none; }
.brand-mark { display: inline-grid; place-items: center; width: 28px; height: 28px; border-radius: 7px; background: var(--accent); color: #fff; font-size: 15px; font-weight: 800; }
.top-nav { display: flex; gap: 14px; margin-left: auto; font-size: 14px; }
.top-nav a { color: var(--fg-soft); }
.icon-btn { background: none; border: 1px solid var(--line); color: var(--fg); border-radius: 8px; width: 36px; height: 36px; cursor: pointer; font-size: 16px; }
.icon-btn:hover { background: var(--bg-soft); }
.menu-btn { display: none; }
.search { position: relative; flex: 0 1 340px; margin-left: 16px; }
.search input { width: 100%; height: 36px; border: 1px solid var(--line); border-radius: 18px; padding: 0 14px; background: var(--bg-soft); color: var(--fg); font: inherit; font-size: 14px; }
.search input:focus { outline: 2px solid var(--accent); background: var(--bg); }
.search-results { position: absolute; top: 42px; left: 0; right: 0; min-width: 320px; max-height: 70vh; overflow: auto; background: var(--bg); border: 1px solid var(--line); border-radius: 10px; box-shadow: 0 10px 30px rgba(0,0,0,.18); padding: 6px; }
.search-results a { display: block; padding: 8px 10px; border-radius: 8px; color: var(--fg); }
.search-results a:hover, .search-results a.sel { background: var(--accent-soft); text-decoration: none; }
.search-results .r-t { font-weight: 600; font-size: 14px; }
.search-results .r-c { font-size: 12px; color: var(--fg-soft); }
.search-results .r-x { font-size: 12.5px; color: var(--fg-soft); line-height: 1.5; margin-top: 2px; }
.search-results mark { background: #ffe58a; color: #000; border-radius: 2px; }
.search-results .empty { padding: 12px; color: var(--fg-soft); font-size: 14px; }

/* layout */
.layout { max-width: 1480px; margin: 0 auto; display: grid; grid-template-columns: var(--sidebar-w) minmax(0, 1fr) 240px; }
.layout.no-toc { grid-template-columns: var(--sidebar-w) minmax(0, 1fr); }
.sidebar { position: sticky; top: var(--header-h); align-self: start; height: calc(100vh - var(--header-h)); overflow-y: auto; padding: 20px 12px 40px 16px; border-right: 1px solid var(--line); font-size: 14.5px; }
.sidebar-title { display: block; font-weight: 700; margin: 0 6px 12px; color: var(--fg); font-size: 15px; }
.chap { margin-bottom: 4px; }
.chap > summary { cursor: pointer; padding: 7px 8px; border-radius: 8px; font-weight: 600; list-style: none; line-height: 1.4; }
.chap > summary::-webkit-details-marker { display: none; }
.chap > summary::before { content: "▸"; display: inline-block; width: 14px; color: var(--fg-soft); transition: transform .15s; }
.chap[open] > summary::before { transform: rotate(90deg); }
.chap > summary:hover { background: var(--bg-soft); }
.chap ul { list-style: none; margin: 2px 0 8px; padding: 0 0 0 14px; border-left: 1px solid var(--line); margin-left: 14px; }
.chap li a { display: block; padding: 5px 10px; border-radius: 6px; color: var(--fg-soft); line-height: 1.45; }
.chap li a:hover { background: var(--bg-soft); color: var(--fg); text-decoration: none; }
.chap li a.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.num { color: var(--fg-soft); font-variant-numeric: tabular-nums; margin-right: 2px; }
.badge { font-style: normal; font-size: 11px; border: 1px solid var(--line); border-radius: 10px; padding: 0 6px; color: var(--fg-soft); }

.doc { padding: 28px 40px 60px; min-width: 0; }
.crumbs { font-size: 13px; color: var(--fg-soft); margin: 0 0 18px; }
.doc-head h1 { font-size: 2rem; line-height: 1.3; margin: 0 0 8px; letter-spacing: -0.01em; }
.lead { font-size: 1.08rem; color: var(--fg-soft); margin: 0 0 8px; }
.meta { font-size: 13px; color: var(--fg-soft); margin: 0 0 24px; padding-bottom: 20px; border-bottom: 1px solid var(--line); }
.toc-col { padding: 28px 16px 40px 0; }
.toc { position: sticky; top: calc(var(--header-h) + 24px); font-size: 13.5px; max-height: calc(100vh - var(--header-h) - 60px); overflow: auto; }
.toc-title { font-weight: 700; margin: 0 0 8px; font-size: 13px; color: var(--fg-soft); }
.toc ul { list-style: none; margin: 0; padding: 0; border-left: 1px solid var(--line); }
.toc li a { display: block; padding: 3px 12px; color: var(--fg-soft); margin-left: -1px; border-left: 2px solid transparent; line-height: 1.45; }
.toc li.l3 a { padding-left: 26px; font-size: 13px; }
.toc li a:hover { color: var(--fg); text-decoration: none; }
.toc li a.on { color: var(--accent); border-left-color: var(--accent); font-weight: 600; }

/* prose */
.prose { max-width: 780px; }
.prose h2 { font-size: 1.5rem; margin: 2.4em 0 .6em; padding-bottom: .3em; border-bottom: 1px solid var(--line); line-height: 1.4; }
.prose h3 { font-size: 1.2rem; margin: 1.9em 0 .5em; line-height: 1.45; }
.prose h4 { font-size: 1.02rem; margin: 1.5em 0 .4em; }
.prose p, .prose ul, .prose ol { margin: 0 0 1.05em; }
.prose li { margin: .25em 0; }
.prose a.anchor { margin-left: -1.1em; padding-right: .35em; opacity: 0; color: var(--fg-soft); font-weight: 400; }
.prose h2:hover a.anchor, .prose h3:hover a.anchor, a.anchor:focus { opacity: 1; }
.prose code { font-family: var(--mono); font-size: .88em; background: var(--bg-code); padding: .12em .4em; border-radius: 5px; word-break: break-all; }
.prose pre { position: relative; margin: 1.2em 0; background: var(--bg-code); border: 1px solid var(--line); border-radius: 10px; padding: 14px 16px; overflow-x: auto; font-size: 13.5px; line-height: 1.6; }
.prose pre code { background: none; padding: 0; font-size: inherit; word-break: normal; white-space: pre; }
.copy-btn { position: absolute; top: 8px; right: 8px; font: 12px var(--font); background: var(--bg); border: 1px solid var(--line); color: var(--fg-soft); border-radius: 6px; padding: 2px 8px; cursor: pointer; opacity: 0; }
.prose pre:hover .copy-btn, .copy-btn:focus { opacity: 1; }
.prose blockquote { margin: 1.2em 0; padding: .2em 1em; border-left: 4px solid var(--line); color: var(--fg-soft); }
.prose hr { border: 0; border-top: 1px solid var(--line); margin: 2em 0; }
.prose img, .prose svg { max-width: 100%; height: auto; }
.prose figure { margin: 1.4em 0; }
.prose figure img { display: block; margin: 0 auto; border-radius: 6px; border: 1px solid var(--line); }
.prose figcaption { font-size: 13px; color: var(--fg-soft); text-align: center; margin-top: 6px; }
.table-wrap { overflow-x: auto; margin: 1.2em 0; }
.prose table { border-collapse: collapse; width: 100%; font-size: 14.5px; }
.prose th, .prose td { border: 1px solid var(--line); padding: 8px 12px; text-align: left; vertical-align: top; }
.prose th { background: var(--bg-soft); white-space: nowrap; }
.callout { margin: 1.4em 0; padding: 12px 18px 4px; border-radius: 10px; border-left: 4px solid; }
.callout-title { font-weight: 700; margin: 0 0 6px !important; font-size: .95em; }
.callout-tip { background: var(--tip-bg); border-color: var(--tip); } .callout-tip .callout-title { color: var(--tip); }
.callout-note { background: var(--note-bg); border-color: var(--note); } .callout-note .callout-title { color: var(--note); }
.callout-warn { background: var(--warn-bg); border-color: var(--warn); } .callout-warn .callout-title { color: var(--warn); }
.callout-exp { background: var(--exp-bg); border-color: var(--exp); } .callout-exp .callout-title { color: var(--exp); }
.callout pre { background: var(--bg); }

.chapter-pages { list-style: none; padding: 0; margin: 28px 0 0; max-width: 780px; display: grid; gap: 10px; }
.chapter-pages a { display: flex; gap: 14px; padding: 14px 16px; border: 1px solid var(--line); border-radius: 12px; color: var(--fg); }
.chapter-pages a:hover { border-color: var(--accent); text-decoration: none; background: var(--bg-soft); }
.chapter-pages small { display: block; color: var(--fg-soft); margin-top: 2px; }
.chapter-pages .num { font-weight: 700; color: var(--accent); min-width: 2.2em; }

.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; max-width: 780px; margin-top: 48px; }
.pager a { display: block; border: 1px solid var(--line); border-radius: 12px; padding: 12px 16px; color: var(--fg); }
.pager a:hover { border-color: var(--accent); text-decoration: none; }
.pager small { display: block; color: var(--fg-soft); font-size: 12px; }
.pager .next { text-align: right; grid-column: 2; }
.pager .prev { grid-column: 1; }

/* home */
.home { max-width: 1000px; margin: 0 auto; padding: 0 20px 60px; }
.hero { padding: 64px 0 36px; }
.eyebrow { color: var(--accent); font-weight: 700; font-size: 13px; letter-spacing: .08em; text-transform: uppercase; margin: 0 0 8px; }
.hero h1 { font-size: clamp(2.2rem, 6vw, 3.4rem); line-height: 1.15; margin: 0 0 10px; letter-spacing: -0.02em; }
.hero-sub { font-size: 1.3rem; color: var(--fg-soft); margin: 0 0 14px; }
.hero p { max-width: 680px; }
.hero-actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 22px; }
.btn { display: inline-block; background: var(--accent); color: #fff; padding: 10px 20px; border-radius: 10px; font-weight: 600; }
.btn:hover { text-decoration: none; opacity: .9; }
.btn.ghost { background: none; color: var(--accent); border: 1px solid var(--accent); }
.hero-meta { color: var(--fg-soft); font-size: 14px; }
.audience { background: var(--bg-soft); border-radius: 14px; padding: 6px 24px 14px; margin: 12px 0 40px; }
.audience ul { padding-left: 1.1em; }
.home-toc h2 { font-size: 1.6rem; border-bottom: 1px solid var(--line); padding-bottom: 8px; }
.home-chap { margin: 28px 0; }
.home-chap h3 { margin: 0 0 4px; font-size: 1.2rem; }
.home-chap h3 a { color: var(--fg); }
.home-chap p { color: var(--fg-soft); margin: 0 0 8px; }
.home-chap ul { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 2px 20px; }
.home-chap li a { display: block; padding: 5px 0; color: var(--fg); }

/* footer */
.site-footer { border-top: 1px solid var(--line); background: var(--bg-soft); margin-top: 20px; }
.footer-inner { max-width: 1100px; margin: 0 auto; padding: 28px 20px; font-size: 14px; color: var(--fg-soft); }
.footer-inner nav { display: flex; flex-wrap: wrap; gap: 6px 18px; margin: 10px 0; }
.footer-inner .copy { font-size: 12.5px; margin-bottom: 0; }

/* hljs */
.hljs-keyword, .hljs-selector-tag, .hljs-built_in { color: #c0392b; }
.hljs-string, .hljs-attr, .hljs-regexp { color: #0f7b4f; }
.hljs-number, .hljs-literal { color: #b45309; }
.hljs-comment, .hljs-quote { color: #8a93a3; font-style: italic; }
.hljs-title, .hljs-section, .hljs-function .hljs-title { color: #2456d6; }
.hljs-variable, .hljs-name { color: #8e44ad; }
:root[data-theme="dark"] .hljs-keyword, :root[data-theme="dark"] .hljs-built_in { color: #ff8f85; }
:root[data-theme="dark"] .hljs-string, :root[data-theme="dark"] .hljs-attr { color: #7fe0b0; }
:root[data-theme="dark"] .hljs-number { color: #f0b45a; }
:root[data-theme="dark"] .hljs-title { color: #8fb0ff; }
:root[data-theme="dark"] .hljs-variable { color: #c3a2f5; }

.scrim { position: fixed; inset: var(--header-h) 0 0 0; background: rgba(0,0,0,.45); z-index: 39; }

@media (max-width: 1180px) {
  .layout { grid-template-columns: var(--sidebar-w) minmax(0, 1fr); }
  .toc-col { display: none; }
}
@media (max-width: 860px) {
  .menu-btn { display: inline-block; }
  .layout, .layout.no-toc { grid-template-columns: minmax(0, 1fr); }
  .sidebar { position: fixed; z-index: 40; left: 0; top: var(--header-h); width: min(86vw, 340px); background: var(--bg); transform: translateX(-100%); transition: transform .2s; border-right: 1px solid var(--line); }
  .sidebar.open { transform: none; }
  .doc { padding: 20px 16px 48px; }
  .doc-head h1 { font-size: 1.6rem; }
  .top-nav { display: none; }
  .search { flex: 1; margin-left: 0; }
  .brand span:last-child { display: none; }
  .pager { grid-template-columns: 1fr; }
  .pager .next, .pager .prev { grid-column: 1; text-align: left; }
  .prose a.anchor { display: none; }
}
@media print {
  .site-header, .sidebar, .toc-col, .pager, .site-footer, .scrim { display: none !important; }
  .layout { display: block; }
}

/* diagrams (inline SVG) */
.dg { display: block; width: 100%; max-width: 720px; height: auto; margin: 0 auto; }
.dg-box { fill: var(--bg-soft); stroke: var(--fg-soft); stroke-width: 1.2; }
.dg-acc { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.4; }
.dg-warn { fill: var(--warn-bg); stroke: var(--warn); stroke-width: 1.4; }
.dg-tip { fill: var(--tip-bg); stroke: var(--tip); stroke-width: 1.4; }
.dg-ln { stroke: var(--fg-soft); stroke-width: 1.4; fill: none; }
.dg-t { fill: var(--fg); font: 600 13px var(--font); }
.dg-s { fill: var(--fg-soft); font: 11.5px var(--font); }
.dg-m { fill: var(--fg); font: 12px var(--mono); }