:root {
  --bg: #faf9f6;
  --surface: #ffffff;
  --fg: #1c1c1e;
  --muted: #6a6a70;
  --line: #e6e3db;
  --accent: #c2410c;
  --accent-soft: #fdeee6;
  --code-bg: #f5f3ee;
  --code-fg: #24292f;
  --ln: #a3a19a;
  --add-bg: #e6f6ea;
  --add-ln: #cdeed4;
  --add-sign: #1a7f37;
  --del-bg: #fdecec;
  --del-ln: #f8d4d4;
  --del-sign: #cf222e;
  --out-bg: #1f2328;
  --out-fg: #e6edf3;
  /* syntax */
  --t-kw: #cf222e;
  --t-fn: #8250df;
  --t-cls: #953800;
  --t-str: #0a3069;
  --t-num: #0550ae;
  --t-com: #6e7781;
  --t-bi: #0550ae;
  --t-dec: #8250df;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #131315;
    --surface: #1b1b1e;
    --fg: #e9e7e2;
    --muted: #9a988f;
    --line: #2c2c30;
    --accent: #fb923c;
    --accent-soft: #3a2416;
    --code-bg: #18181b;
    --code-fg: #e6edf3;
    --ln: #5c5c63;
    --add-bg: #12261a;
    --add-ln: #173422;
    --add-sign: #3fb950;
    --del-bg: #2d1416;
    --del-ln: #3d1a1d;
    --del-sign: #f85149;
    --out-bg: #0d0d0f;
    --out-fg: #d8dee4;
    --t-kw: #ff7b72;
    --t-fn: #d2a8ff;
    --t-cls: #ffa657;
    --t-str: #a5d6ff;
    --t-num: #79c0ff;
    --t-com: #8b949e;
    --t-bi: #79c0ff;
    --t-dec: #d2a8ff;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: "Pretendard Variable", Pretendard, -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", "Noto Sans KR", sans-serif;
  font-size: 16.5px;
  line-height: 1.75;
  word-break: keep-all;
  overflow-wrap: break-word;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code, pre, kbd, .code {
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "D2Coding", monospace;
}
:not(pre) > code {
  font-size: 0.88em;
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: 0.05em 0.35em;
}
kbd {
  font-size: 0.8em;
  border: 1px solid var(--line);
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 0 0.4em;
  background: var(--surface);
}

/* ── layout ─────────────────────────────────── */
.progress { position: fixed; top: 0; left: 0; right: 0; height: 3px; z-index: 10; background: transparent; }
.progress span { display: block; height: 100%; background: var(--accent); }
.layout { display: grid; grid-template-columns: 272px minmax(0, 1fr); min-height: 100vh; }
.side {
  position: sticky; top: 0; height: 100vh; overflow-y: auto;
  border-right: 1px solid var(--line);
  padding: 28px 18px 40px;
  font-size: 14px;
  line-height: 1.45;
}
.brand { display: block; color: var(--muted); font-size: 13px; letter-spacing: 0.02em; margin-bottom: 18px; }
.brand b { color: var(--fg); font-size: 17px; }
.brand:hover { text-decoration: none; }
.toc > summary { display: none; }
.side .part { font-size: 12px; font-weight: 700; color: var(--muted); margin: 18px 0 6px; letter-spacing: 0.04em; }
.side ol { list-style: none; margin: 0; padding: 0; }
.side li a {
  display: flex; gap: 10px; padding: 6px 8px; border-radius: 6px; color: var(--fg);
}
.side li a:hover { background: var(--code-bg); text-decoration: none; }
.side li a[aria-current="page"] { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.side .num { font-variant-numeric: tabular-nums; color: var(--muted); font-size: 12px; padding-top: 1px; }
.side li a[aria-current="page"] .num { color: var(--accent); }

main { padding: 48px 56px 64px; max-width: 1040px; width: 100%; }

/* ── typography ─────────────────────────────── */
.kicker { font-size: 12.5px; font-weight: 700; letter-spacing: 0.12em; color: var(--accent); }
.kicker span { color: var(--muted); font-weight: 500; }
h1 { font-size: 34px; line-height: 1.3; margin: 8px 0 24px; letter-spacing: -0.02em; }
h2 { font-size: 21px; margin: 0; letter-spacing: -0.01em; }
.prose h2 { margin: 36px 0 12px; }
.prose h3 { font-size: 17px; margin: 20px 0 6px; }
.notes .prose h3:first-child { margin-top: 12px; }
.prose p, .prose ul, .prose ol { margin: 0 0 16px; }
.prose li { margin: 4px 0; }
article.prose > ul:first-child { list-style: none; padding: 0; color: var(--muted); font-size: 14.5px; }
.prose img { display: block; max-width: min(100%, 340px); height: auto; margin: 20px auto; background: #fff; border-radius: 8px; padding: 12px; }
.prose blockquote {
  margin: 20px 0; padding: 12px 18px; border-left: 3px solid var(--accent);
  background: var(--surface); border-radius: 0 8px 8px 0; color: var(--muted); font-size: 15px;
}
.prose blockquote p { margin: 0; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 6px 0; }
.hint { color: var(--muted); font-size: 14px; margin: 4px 0 12px; }

/* ── blocks ─────────────────────────────────── */
.block { margin-top: 44px; }
.block-head { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; flex-wrap: wrap; border-bottom: 1px solid var(--line); padding-bottom: 8px; margin-bottom: 8px; }
.stat { font-size: 13.5px; color: var(--muted); font-variant-numeric: tabular-nums; }
.plus { color: var(--add-sign); font-weight: 700; }
.minus { color: var(--del-sign); font-weight: 700; }
.tabs { display: flex; gap: 4px; align-items: center; margin: 12px 0 0; flex-wrap: wrap; }
.tabs button {
  font: inherit; font-size: 14px; border: 1px solid var(--line); border-bottom: none;
  background: transparent; color: var(--muted); padding: 6px 14px; border-radius: 8px 8px 0 0; cursor: pointer;
}
.tabs button[aria-selected="true"] { background: var(--code-bg); color: var(--fg); font-weight: 600; }
.tabs .src { margin-left: auto; font-size: 13.5px; }
.tabpanel { border: 1px solid var(--line); border-radius: 0 8px 8px 8px; background: var(--code-bg); overflow: auto; }
.tabpanel[data-panel="full"] { max-height: 80vh; }

/* ── code table ─────────────────────────────── */
.code { border-collapse: collapse; width: 100%; font-size: 13px; line-height: 1.6; color: var(--code-fg); }
.code td { padding: 0; vertical-align: top; }
.code .ln {
  width: 1%; min-width: 3.2em; padding: 0 8px; text-align: right; color: var(--ln);
  user-select: none; font-variant-numeric: tabular-nums; white-space: nowrap;
}
.code .sg { width: 1%; padding: 0 6px 0 2px; user-select: none; text-align: center; font-weight: 700; }
.code .cd { white-space: pre; padding-right: 16px; }
.code tr.add { background: var(--add-bg); }
.code tr.add .ln { background: var(--add-ln); }
.code tr.add .sg { color: var(--add-sign); }
.code tr.del { background: var(--del-bg); }
.code tr.del .ln { background: var(--del-ln); }
.code tr.del .sg { color: var(--del-sign); }
.code tr.del .cd { opacity: 0.75; }
.code tr:first-child td { padding-top: 10px; }
.code tr:last-child td { padding-bottom: 10px; }
.code.full .ln { min-width: 3.6em; }
.diff tbody.hidden { display: none; }
.diff tbody.fold td { padding: 2px 0; background: var(--bg); }
.diff tbody.fold button {
  width: 100%; font: inherit; font-size: 12.5px; color: var(--muted); background: transparent;
  border: none; border-top: 1px dashed var(--line); border-bottom: 1px dashed var(--line); padding: 4px; cursor: pointer;
}
.diff tbody.fold button:hover { color: var(--accent); }

.code .k, .code .kn, .code .kc, .code .kd, .code .kr, .code .ow { color: var(--t-kw); }
.code .nf, .code .fm { color: var(--t-fn); }
.code .nc { color: var(--t-cls); }
.code .s, .code .s1, .code .s2, .code .sd, .code .sa, .code .si, .code .se, .code .dl, .code .sb { color: var(--t-str); }
.code .mi, .code .mf, .code .m { color: var(--t-num); }
.code .c, .code .c1, .code .cm { color: var(--t-com); font-style: italic; }
.code .nb, .code .bp { color: var(--t-bi); }
.code .nd { color: var(--t-dec); }

/* ── output ─────────────────────────────────── */
.demo { margin: 12px 0; border: 1px solid var(--line); border-radius: 8px; background: var(--code-bg); }
.demo > summary { cursor: pointer; padding: 8px 14px; font-size: 14px; color: var(--muted); }
.demo[open] > summary { border-bottom: 1px solid var(--line); }
.demo .code { max-height: 60vh; }
.demo > .code { display: block; overflow: auto; max-height: 60vh; }
pre.out {
  margin: 12px 0; padding: 14px 16px; border-radius: 8px; background: var(--out-bg); color: var(--out-fg);
  font-size: 12.8px; line-height: 1.55; overflow: auto; max-height: 70vh; white-space: pre;
}
.chart { display: block; max-width: 100%; margin: 12px 0; padding: 14px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface); overflow-x: auto; min-height: 120px; }
.chart-loading { color: var(--muted); font-size: 14px; }
.note { font-size: 14.5px; border: 1px solid var(--line); background: var(--accent-soft); border-radius: 8px; padding: 10px 16px; margin: 12px 0; }
.note p { margin: 0; }

/* ── pager ──────────────────────────────────── */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 56px; }
.pager a {
  display: flex; flex-direction: column; gap: 2px; padding: 14px 18px; border: 1px solid var(--line);
  border-radius: 10px; color: var(--fg); background: var(--surface); font-weight: 600; line-height: 1.4;
}
.pager a:hover { border-color: var(--accent); text-decoration: none; }
.pager small { color: var(--muted); font-weight: 500; font-size: 12.5px; }
.pager .next { text-align: right; }
.foot { margin-top: 48px; padding-top: 16px; border-top: 1px solid var(--line); color: var(--muted); font-size: 13px; }

/* ── index ──────────────────────────────────── */
.hero h1 { font-size: 40px; margin: 12px 0 20px; }
.lede { font-size: 17.5px; color: var(--fg); max-width: 760px; }
.cta { display: flex; align-items: center; gap: 18px; margin-top: 24px; flex-wrap: wrap; }
.btn { background: var(--accent); color: #fff; padding: 11px 20px; border-radius: 10px; font-weight: 700; }
.btn:hover { text-decoration: none; filter: brightness(1.08); }
:root:not([data-theme="light"]) .btn { color: #1a0f08; }
@media (prefers-color-scheme: light) { :root .btn { color: #fff; } }
.kbd-hint { color: var(--muted); font-size: 14px; }
.growth { margin-top: 56px; }
.growth h2 { margin-bottom: 18px; }
.bars { display: flex; align-items: flex-end; gap: 6px; height: 180px; border-bottom: 1px solid var(--line); padding-bottom: 0; }
.bar { flex: 1; height: 100%; display: flex; flex-direction: column; justify-content: flex-end; align-items: center; position: relative; }
.bar .fill { width: 100%; height: var(--h); min-height: 3px; background: var(--accent); opacity: 0.8; border-radius: 4px 4px 0 0; transition: opacity .15s; }
.bar:hover .fill { opacity: 1; }
.bar .lbl { position: absolute; bottom: -22px; font-size: 11.5px; color: var(--muted); font-variant-numeric: tabular-nums; }
.growth .hint { margin-top: 30px; }
.howto { margin-top: 40px; }
.howto figure { margin: 24px 0 0; text-align: center; }
.howto figure img { max-width: 100%; height: auto; background: #fff; border-radius: 8px; padding: 12px; }
.howto figcaption { font-size: 13.5px; color: var(--muted); margin-top: 6px; }
.part-block { margin-top: 44px; }
.part-block h2 { margin-bottom: 14px; }
.cards { list-style: none; padding: 0; margin: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 10px; }
.cards a {
  display: grid; grid-template-columns: auto 1fr; column-gap: 12px; row-gap: 2px; padding: 14px 16px;
  border: 1px solid var(--line); border-radius: 10px; background: var(--surface); color: var(--fg); height: 100%;
}
.cards a:hover { border-color: var(--accent); text-decoration: none; }
.cards .num { grid-row: span 3; font-size: 22px; font-weight: 800; color: var(--accent); font-variant-numeric: tabular-nums; line-height: 1.2; }
.cards .t { font-weight: 700; line-height: 1.4; }
.cards .d { font-size: 14px; color: var(--muted); line-height: 1.45; }
.cards .lines { font-size: 12px; color: var(--muted); font-variant-numeric: tabular-nums; }

/* ── mobile ─────────────────────────────────── */
@media (max-width: 900px) {
  .layout { display: block; }
  .side {
    position: sticky; top: 0; height: auto; max-height: 100vh; z-index: 5; border-right: none;
    border-bottom: 1px solid var(--line); background: var(--bg); padding: 10px 16px;
  }
  .brand { display: none; }
  .toc > summary { display: block; cursor: pointer; font-weight: 600; font-size: 14.5px; padding: 4px 0; }
  .toc[open] { max-height: 80vh; overflow-y: auto; padding-bottom: 10px; }
  main { padding: 28px 16px 48px; }
  h1 { font-size: 27px; }
  .hero h1 { font-size: 30px; }
  .code { font-size: 12px; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { text-align: left; }
  .bars { gap: 3px; height: 140px; }
  .bar .lbl { font-size: 10px; }
}

/* ── 인라인 그림 ─────────────────────────────── */
.fig { margin: 16px 0 28px; padding: 16px; border: 1px solid var(--line); border-radius: 10px; background: var(--surface); }
.fig svg { display: block; width: 100%; max-width: 640px; height: auto; margin: 0 auto; }
.fig text { fill: var(--fg); font-size: 14px; font-family: "Pretendard Variable", Pretendard, -apple-system, sans-serif; }
.fig .num { font-size: 18px; font-weight: 700; }
.fig .muted { fill: var(--muted); font-size: 12.5px; }
.fig .mono { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 13px; }
.fig .strong { font-weight: 700; }
.fig .box { fill: var(--surface); stroke: var(--muted); stroke-width: 1.2; }
.fig .tbl { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.6; }
.fig .grp { fill: var(--code-bg); stroke: var(--muted); stroke-width: 1.2; stroke-dasharray: 4 3; }
.fig .bad { fill: var(--del-bg); stroke: var(--del-sign); stroke-width: 1.6; }
.fig .good { fill: var(--add-bg); stroke: var(--add-sign); stroke-width: 1.6; }
.fig .hit { fill: var(--accent); }
.fig .grid { stroke: var(--accent); stroke-opacity: 0.25; }
.fig .line { stroke: var(--muted); stroke-width: 1.5; fill: none; }
.fig .arrowhead { fill: var(--muted); }
.fig .t-bad { fill: var(--del-sign); font-weight: 600; }
.fig .t-good { fill: var(--add-sign); font-weight: 600; }
@media (max-width: 900px) { .fig { padding: 10px 6px; } }

.fig .num-s { font-size: 15px; font-weight: 700; }
.fig .tiny { fill: var(--muted); font-size: 10.5px; }
.fig .ax-b { fill: var(--muted); fill-opacity: 0.08; stroke: var(--muted); stroke-width: 1.2; }
.fig .ax-t { fill: var(--accent); fill-opacity: 0.12; stroke: var(--accent); stroke-width: 1.4; }
.fig .ax-h { fill: var(--t-fn); fill-opacity: 0.12; stroke: var(--t-fn); stroke-width: 1.4; }
.fig .ax-d { fill: var(--t-num); fill-opacity: 0.10; stroke: var(--t-num); stroke-width: 1.4; }
.fig .attn-box { fill: none; stroke: var(--accent); stroke-width: 1.2; stroke-dasharray: 5 4; }
.fig .attn-label { fill: var(--accent); font-size: 12px; }
.fig .attn-label-bg { fill: var(--surface); }
.fig .seg { fill-opacity: 0.55; }
.fig .seg-frame { fill: none; stroke: var(--t-num); stroke-width: 1.4; }
.fig .fan { stroke: var(--fg); stroke-opacity: 0.45; stroke-width: 1; }
.fig .pick { fill: none; stroke: var(--fg); stroke-width: 2; }