:root {
  --bg: #ffffff;
  --bg-soft: #f7f6f3;
  --bg-hover: #f0eee9;
  --line: #e7e4dd;
  --text: #1f1a24;
  --text-2: #5d5566;
  --text-3: #8f8798;
  --accent: #d94a3d;
  --accent-soft: #fdeceA;
  --gold: #ffd23f;
  --ink: #1b1020;
  --code-bg: #1d1626;
  --code-fg: #f5e9d6;
  --mark: #fff2b3;
  --shadow: 0 20px 60px rgba(27,16,32,.18);
  --sans: 'Inter', system-ui, -apple-system, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, monospace;
  --pixel: 'Press Start 2P', monospace;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #15111b; --bg-soft: #1c1724; --bg-hover: #251f2f; --line: #2e2739;
    --text: #efe9f4; --text-2: #b7aec2; --text-3: #7f768c;
    --accent: #ff6b5c; --accent-soft: #3a1c22; --code-bg: #0e0a13; --mark: #5a4a12;
    --shadow: 0 20px 60px rgba(0,0,0,.5);
  }
}
:root[data-theme="dark"] {
  --bg: #15111b; --bg-soft: #1c1724; --bg-hover: #251f2f; --line: #2e2739;
  --text: #efe9f4; --text-2: #b7aec2; --text-3: #7f768c;
  --accent: #ff6b5c; --accent-soft: #3a1c22; --code-bg: #0e0a13; --mark: #5a4a12;
  --shadow: 0 20px 60px rgba(0,0,0,.5);
}

* { box-sizing: border-box; }
html { scroll-padding-top: 90px; }
body { margin: 0; background: var(--bg); color: var(--text); font-family: var(--sans); font-size: 16px; line-height: 1.7; transition: background .3s, color .3s; }
a { color: inherit; }
svg { display: block; }
::selection { background: var(--gold); color: var(--ink); }

.read-progress { position: fixed; top: 0; left: 0; height: 3px; width: 0; background: var(--accent); z-index: 60; transition: width .1s; }

/* ---------- top bar ---------- */
.topbar { position: sticky; top: 0; z-index: 40; background: color-mix(in srgb, var(--bg) 86%, transparent); backdrop-filter: blur(12px); border-bottom: 1px solid var(--line); }
.roof-edge { height: 8px; background:
  linear-gradient(90deg, var(--accent) 0 50%, #b8362c 50% 100%) 0 0 / 16px 4px repeat-x,
  linear-gradient(90deg, #b8362c 0 50%, var(--accent) 50% 100%) 0 4px / 16px 4px repeat-x; }
.topbar-inner { display: flex; align-items: center; gap: 16px; height: 60px; padding: 0 20px; max-width: 1440px; margin: 0 auto; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; flex-shrink: 0; }
.brand-logo { height: 34px; width: auto; image-rendering: pixelated; transition: transform .3s cubic-bezier(.3,1.6,.5,1); }
.brand:hover .brand-logo { transform: translateY(-2px) rotate(-2deg); }
.brand-text { font-family: var(--pixel); font-size: 12px; letter-spacing: .5px; }
.brand-text em { font-style: normal; color: var(--text-3); margin-left: 4px; font-size: 10px; }
.search-trigger { flex: 1; max-width: 380px; margin-left: auto; display: flex; align-items: center; gap: 10px; height: 38px; padding: 0 12px; border: 1px solid var(--line); border-radius: 10px; background: var(--bg-soft); color: var(--text-3); font: inherit; font-size: 14px; cursor: pointer; transition: border-color .2s, box-shadow .2s; }
.search-trigger:hover { border-color: var(--accent); box-shadow: 0 0 0 4px var(--accent-soft); }
.search-trigger .st-label { flex: 1; text-align: left; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
kbd { font-family: var(--mono); font-size: 11px; padding: 2px 6px; border: 1px solid var(--line); border-bottom-width: 2px; border-radius: 5px; color: var(--text-3); background: var(--bg); }
.top-links { display: flex; align-items: center; gap: 4px; }
.top-links a { font-size: 14px; font-weight: 500; text-decoration: none; padding: 7px 10px; border-radius: 8px; color: var(--text-2); }
.top-links a:hover { background: var(--bg-hover); color: var(--text); }
.top-links a.cta { background: var(--ink); color: var(--gold); font-family: var(--pixel); font-size: 9px; padding: 10px 12px; border-radius: 0; box-shadow: 0 -2px 0 var(--ink), 3px 3px 0 var(--accent); transition: transform .15s; }
.top-links a.cta:hover { transform: translate(-1px, -2px); background: var(--ink); color: var(--gold); }
.icon-btn { width: 38px; height: 38px; border: 1px solid var(--line); background: var(--bg); color: var(--text-2); border-radius: 10px; cursor: pointer; font-size: 17px; display: grid; place-items: center; flex-shrink: 0; }
.icon-btn:hover { background: var(--bg-hover); color: var(--text); }
.menu-btn { display: none; }

/* ---------- layout ---------- */
.layout { display: grid; grid-template-columns: 280px minmax(0, 1fr) 240px; max-width: 1440px; margin: 0 auto; }
.sidebar, .toc { position: sticky; top: 69px; height: calc(100vh - 69px); overflow-y: auto; padding: 28px 16px 40px; }
.sidebar { border-right: 1px solid var(--line); }
.side-label { font-size: 11px; font-weight: 700; letter-spacing: .08em; text-transform: uppercase; color: var(--text-3); padding: 0 10px 10px; }
.nav-item { display: flex; align-items: flex-start; gap: 8px; padding: 6px 10px; border-radius: 8px; text-decoration: none; font-size: 14px; color: var(--text-2); line-height: 1.45; position: relative; transition: background .15s, color .15s; }
.nav-item:hover { background: var(--bg-hover); color: var(--text); }
.nav-item .num { font-family: var(--mono); font-size: 11px; color: var(--text-3); min-width: 18px; padding-top: 2px; }
.nav-item.active { color: var(--accent); background: var(--accent-soft); font-weight: 600; }
.nav-item.active .num { color: var(--accent); }
.nav-item.active::before { content: ''; position: absolute; left: -16px; top: 8px; width: 4px; height: 16px; background: var(--accent); animation: grow .3s cubic-bezier(.3,1.5,.5,1); }
@keyframes grow { from { transform: scaleY(0); } }
.subnav { margin: 2px 0 6px 28px; border-left: 1px solid var(--line); overflow: hidden; animation: open .35s ease; }
@keyframes open { from { opacity: 0; transform: translateY(-6px); } }
.subnav a { display: block; padding: 4px 12px; font-size: 13px; color: var(--text-3); text-decoration: none; border-left: 2px solid transparent; margin-left: -1px; }
.subnav a:hover { color: var(--text); }
.subnav a.on { color: var(--accent); border-left-color: var(--accent); }
.side-foot { display: flex; gap: 10px; align-items: center; margin: 26px 10px 0; padding: 12px; border: 1px dashed var(--line); border-radius: 10px; font-size: 12px; color: var(--text-3); line-height: 1.5; }
.side-foot svg { width: 22px; flex-shrink: 0; }

/* ---------- content ---------- */
.content { padding: 36px clamp(20px, 5vw, 72px) 80px; min-width: 0; }
.crumbs { font-size: 13px; color: var(--text-3); display: flex; gap: 8px; align-items: center; margin-bottom: 10px; max-width: 760px; margin-inline: auto; }
.crumbs a { text-decoration: none; } .crumbs a:hover { color: var(--accent); }
.doc { max-width: 760px; margin: 0 auto; }
.doc.enter { animation: page-in .45s cubic-bezier(.2,.8,.2,1); }
@keyframes page-in { from { opacity: 0; transform: translateY(14px); } }
.doc h1 { font-size: clamp(30px, 4vw, 40px); line-height: 1.2; letter-spacing: -.02em; margin: 0 0 8px; }
.doc .page-kicker { font-family: var(--pixel); font-size: 10px; color: var(--accent); display: inline-flex; gap: 8px; align-items: center; margin-bottom: 14px; }
.doc .page-kicker svg { width: 16px; }
.doc .lead { font-size: 19px; color: var(--text-2); margin: 6px 0 28px; }
.doc h2 { font-size: 24px; letter-spacing: -.01em; margin: 44px 0 12px; }
.doc h3 { font-size: 20px; letter-spacing: -.01em; margin: 40px 0 10px; padding-top: 8px; position: relative; }
.doc h3 .anchor { position: absolute; left: -24px; opacity: 0; color: var(--text-3); text-decoration: none; font-weight: 400; transition: opacity .15s; }
.doc h3:hover .anchor { opacity: 1; }
.doc h3.flash { animation: flash 1.4s ease; }
@keyframes flash { 0%, 40% { background: var(--mark); } }
.doc p, .doc li { color: var(--text); }
.doc ul, .doc ol { padding-left: 22px; }
.doc li { margin: 6px 0; }
.doc li::marker { color: var(--accent); }
.doc strong { font-weight: 650; }
.doc a { color: var(--accent); text-decoration: underline; text-decoration-color: color-mix(in srgb, var(--accent) 35%, transparent); text-underline-offset: 3px; }
.doc a:hover { text-decoration-color: var(--accent); }
.doc code { font-family: var(--mono); font-size: .88em; background: var(--bg-soft); border: 1px solid var(--line); padding: 1px 6px; border-radius: 6px; }
.doc pre { position: relative; background: var(--code-bg); color: var(--code-fg); padding: 20px 22px; border-radius: 12px; overflow-x: auto; font-size: 14px; line-height: 1.6; margin: 22px 0; border: 1px solid var(--line); }
.doc pre code { background: none; border: 0; padding: 0; color: inherit; font-size: inherit; }
.doc pre .copy { position: absolute; top: 10px; right: 10px; font: 600 11px var(--sans); color: #cbbfd8; background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.12); border-radius: 6px; padding: 4px 8px; cursor: pointer; opacity: 0; transition: opacity .15s; }
.doc pre:hover .copy { opacity: 1; }
.doc pre::before { content: 'formula'; position: absolute; top: 10px; left: 22px; font: 600 10px var(--sans); letter-spacing: .1em; text-transform: uppercase; color: #8d7fa0; }
.doc pre code { display: block; padding-top: 16px; }
.table-wrap { overflow-x: auto; margin: 22px 0; border: 1px solid var(--line); border-radius: 12px; }
.doc table { border-collapse: collapse; width: 100%; font-size: 14px; }
.doc th { text-align: left; font-weight: 600; background: var(--bg-soft); color: var(--text-2); font-size: 13px; }
.doc th, .doc td { padding: 10px 14px; border-bottom: 1px solid var(--line); vertical-align: top; }
.doc tr:last-child td { border-bottom: 0; }
.doc tbody tr { transition: background .15s; }
.doc tbody tr:hover { background: var(--bg-soft); }
.hint { display: flex; gap: 14px; padding: 16px 18px; margin: 22px 0; border-radius: 12px; background: var(--accent-soft); border: 1px solid color-mix(in srgb, var(--accent) 25%, transparent); }
.hint svg { width: 22px; flex-shrink: 0; margin-top: 2px; }
.hint p { margin: 0; }
.cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px; margin: 24px 0; }
.card { display: block; padding: 16px 18px; border: 1px solid var(--line); border-radius: 12px; text-decoration: none !important; color: var(--text) !important; transition: border-color .2s, transform .2s, box-shadow .2s; }
.card:hover { border-color: var(--accent); transform: translateY(-2px); box-shadow: 0 10px 30px rgba(217,74,61,.12); }
.card .n { font-family: var(--pixel); font-size: 9px; color: var(--accent); }
.card .t { display: block; font-weight: 600; margin-top: 6px; }

.pager { max-width: 760px; margin: 56px auto 0; display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.pager a { display: block; padding: 16px 18px; border: 1px solid var(--line); border-radius: 12px; text-decoration: none; transition: border-color .2s, transform .2s; }
.pager a:hover { border-color: var(--accent); transform: translateY(-2px); }
.pager small { display: block; font-size: 12px; color: var(--text-3); }
.pager span { font-weight: 600; color: var(--text); }
.pager a.next { text-align: right; grid-column: 2; }
.doc-foot { max-width: 760px; margin: 40px auto 0; padding-top: 22px; border-top: 1px solid var(--line); display: flex; align-items: center; gap: 10px; flex-wrap: wrap; font-size: 13px; color: var(--text-3); }
.react { font: inherit; font-size: 13px; padding: 5px 10px; border: 1px solid var(--line); border-radius: 999px; background: var(--bg); color: var(--text-2); cursor: pointer; transition: transform .2s cubic-bezier(.3,1.8,.5,1); }
.react:hover { transform: scale(1.08); }
.react.on { border-color: var(--accent); color: var(--accent); }
.doc-foot .updated { margin-left: auto; }

/* ---------- toc ---------- */
.toc { padding-top: 40px; }
.toc a { display: block; font-size: 13px; padding: 4px 10px; color: var(--text-3); text-decoration: none; border-left: 2px solid var(--line); transition: color .15s, border-color .15s; }
.toc a:hover { color: var(--text); }
.toc a.on { color: var(--accent); border-left-color: var(--accent); }
.toc .empty { font-size: 13px; color: var(--text-3); padding: 0 10px; }

/* ---------- search ---------- */
.search-modal { position: fixed; inset: 0; z-index: 100; background: rgba(15,10,20,.45); backdrop-filter: blur(4px); display: none; align-items: flex-start; justify-content: center; padding: 12vh 16px 16px; }
.search-modal.open { display: flex; animation: fade .2s; }
@keyframes fade { from { opacity: 0; } }
.search-box { width: min(640px, 100%); background: var(--bg); border: 1px solid var(--line); border-radius: 14px; box-shadow: var(--shadow); overflow: hidden; animation: drop .25s cubic-bezier(.2,.9,.3,1.2); }
@keyframes drop { from { transform: translateY(-12px) scale(.98); } }
.search-input { display: flex; align-items: center; gap: 10px; padding: 0 16px; border-bottom: 1px solid var(--line); color: var(--text-3); }
.search-input input { flex: 1; height: 56px; border: 0; outline: 0; background: transparent; color: var(--text); font: inherit; font-size: 17px; }
.search-results { max-height: 50vh; overflow-y: auto; padding: 8px; }
.search-results a { display: block; padding: 10px 12px; border-radius: 8px; text-decoration: none; }
.search-results a:hover, .search-results a.sel { background: var(--accent-soft); }
.search-results .r-t { font-weight: 600; font-size: 14px; }
.search-results .r-p { font-size: 12px; color: var(--text-3); }
.search-results .r-s { font-size: 13px; color: var(--text-2); margin-top: 2px; }
.search-results mark { background: var(--mark); color: inherit; border-radius: 3px; padding: 0 1px; }
.search-results .none { padding: 26px; text-align: center; color: var(--text-3); font-size: 14px; }

.scrim { display: none; }

/* ---------- responsive ---------- */
@media (max-width: 1180px) {
  .layout { grid-template-columns: 260px minmax(0, 1fr); }
  .toc { display: none; }
}
@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .menu-btn { display: grid; }
  .top-links a:not(.cta) { display: none; }
  .sidebar { position: fixed; top: 0; left: 0; bottom: 0; height: 100vh; width: 290px; z-index: 70; background: var(--bg); transform: translateX(-100%); transition: transform .3s cubic-bezier(.2,.8,.2,1); box-shadow: var(--shadow); }
  .sidebar.open { transform: none; }
  .scrim { display: block; position: fixed; inset: 0; z-index: 65; background: rgba(15,10,20,.4); opacity: 0; pointer-events: none; transition: opacity .3s; }
  .scrim.open { opacity: 1; pointer-events: auto; }
  .search-trigger .st-label, .search-trigger kbd { display: none; }
  .search-trigger { flex: 0 0 38px; width: 38px; padding: 0; justify-content: center; }
  .brand-text em { display: none; }
  .cards { grid-template-columns: 1fr; }
}
@media (max-width: 480px) {
  .topbar-inner { padding: 0 12px; gap: 8px; }
  .top-links a.cta { display: none; }
  .content { padding: 24px 16px 60px; }
  .pager { grid-template-columns: 1fr; }
  .pager a.next { grid-column: 1; }
  .doc h3 .anchor { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .001ms !important; transition-duration: .001ms !important; }
}