/* Layout: a survey sheet. Hero = the app as a walked map; below, a two-column field manual (index rail + chapters). */
:root {
  --paper: #f1f4f3;
  --sheet: #ffffff;
  --ink: #0f1c24;
  --ink-2: #3d4c55;
  --ink-3: #6b7a83;
  --line: #d5dddd;
  --line-2: #b9c5c6;
  --accent: #2741d8;
  --accent-soft: #e3e7fb;
  --code-bg: #0f1c24;
  --code-ink: #dfe7ea;
  --code-dim: #8a9ba4;
  --err: #cc3a26;
  --warn: #a8700f;
  --ok: #23805a;
  --grid: rgba(15, 28, 36, .05);
  --f-display: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --f-body: "IBM Plex Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0c1317; --sheet: #121b20; --ink: #e2e9ec; --ink-2: #aab8be; --ink-3: #7d8d95;
    --line: #233139; --line-2: #34454e; --accent: #8fa0ff; --accent-soft: #1c2546;
    --code-bg: #081014; --code-ink: #dfe7ea; --code-dim: #7d8d95;
    --err: #ff7a66; --warn: #e3ac4b; --ok: #5fc596; --grid: rgba(226, 233, 236, .04);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #0c1317; --sheet: #121b20; --ink: #e2e9ec; --ink-2: #aab8be; --ink-3: #7d8d95;
  --line: #233139; --line-2: #34454e; --accent: #8fa0ff; --accent-soft: #1c2546;
  --code-bg: #081014; --code-ink: #dfe7ea; --code-dim: #7d8d95;
  --err: #ff7a66; --warn: #e3ac4b; --ok: #5fc596; --grid: rgba(226, 233, 236, .04);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }
body {
  margin: 0; background: var(--paper); color: var(--ink);
  font: 400 16px/1.6 var(--f-body);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--accent); text-underline-offset: 3px; }
a:focus-visible, button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 3px; }
code, pre, kbd { font-family: var(--f-mono); }
:not(pre) > code { font-size: .88em; background: var(--accent-soft); color: var(--ink); padding: .1em .35em; border-radius: 3px; overflow-wrap: anywhere; }
h1, h2, h3 { font-family: var(--f-display); text-wrap: balance; margin: 0; }

.wrap { max-width: 1180px; margin: 0 auto; padding-inline: 24px; }
@media (max-width: 600px) { .wrap { padding-inline: 16px; } }

/* Top bar */
.top { position: sticky; top: env(safe-area-inset-top, 0px); z-index: 10; background: color-mix(in srgb, var(--paper) 88%, transparent); backdrop-filter: blur(8px); border-bottom: 1px solid var(--line); }
.top .wrap { display: flex; align-items: center; gap: 24px; height: 56px; }
.brand { font: 800 19px/1 var(--f-display); font-stretch: 125%; color: var(--ink); text-decoration: none; display: flex; align-items: center; gap: 10px; letter-spacing: -.01em; }
.brand svg { width: 22px; height: 22px; }
.top nav { display: flex; gap: 20px; margin-left: auto; font-size: 14px; }
.top nav a { color: var(--ink-2); text-decoration: none; }
.top nav a:hover { color: var(--ink); }
@media (max-width: 600px) { .top nav .hide-sm { display: none; } }

/* Hero */
.hero { position: relative; border-bottom: 1px solid var(--line); background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px); background-size: 24px 24px; }
.hero .wrap { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr); gap: 48px; padding-block: 72px 64px; align-items: center; }
@media (max-width: 920px) { .hero .wrap { grid-template-columns: minmax(0, 1fr); gap: 36px; padding-block: 44px 40px; } }
.eyebrow { font: 500 12px/1 var(--f-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--ink-3); }
.hero h1 { font-size: clamp(40px, 6.2vw, 68px); line-height: .98; font-weight: 800; font-stretch: 125%; letter-spacing: -.025em; margin-top: 18px; }
.hero h1 em { font-style: normal; color: var(--accent); }
.lede { font-size: 18px; color: var(--ink-2); max-width: 34em; margin: 22px 0 0; }
.cta { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 30px; align-items: center; }
.btn { display: inline-flex; align-items: center; gap: 8px; height: 42px; padding: 0 18px; border-radius: 6px; font: 600 15px/1 var(--f-body); text-decoration: none; border: 1px solid transparent; cursor: pointer; }
.btn-primary { background: var(--ink); color: var(--paper); }
.btn-primary:hover { background: var(--accent); }
.btn-ghost { border-color: var(--line-2); color: var(--ink); background: var(--sheet); }
.btn-ghost:hover { border-color: var(--ink-3); }
.cmd { margin-top: 26px; display: flex; align-items: center; gap: 10px; background: var(--code-bg); color: var(--code-ink); border-radius: 6px; padding: 12px 12px 12px 16px; font: 400 14px/1.4 var(--f-mono); max-width: 34em; }
.cmd span { flex: 1; min-width: 0; overflow-x: auto; white-space: nowrap; }
.cmd span::before { content: "$ "; color: var(--code-dim); }

/* The walked map */
.map { background: var(--sheet); border: 1px solid var(--line-2); border-radius: 8px; box-shadow: 0 1px 0 var(--line), 0 18px 40px -24px rgba(15, 28, 36, .35); overflow: hidden; min-width: 0; }
.map-head { display: flex; justify-content: space-between; gap: 12px; padding: 10px 14px; border-bottom: 1px solid var(--line); font: 500 12px/1.3 var(--f-mono); color: var(--ink-3); }
.map-head b { color: var(--ink); font-weight: 500; }
.map svg { display: block; width: 100%; height: auto; }
.map .col { font: 500 9.5px var(--f-mono); fill: var(--ink-3); letter-spacing: .08em; }
.map .edge { fill: none; stroke: var(--line-2); stroke-width: 1.5; }
.map .edge.on { stroke: var(--accent); stroke-width: 2; }
.map .node rect { fill: var(--sheet); stroke: var(--ink-3); stroke-width: 1.2; }
.map .node.overlay rect { stroke-dasharray: 4 3; }
.map .node.err rect { stroke: var(--err); stroke-width: 1.6; }
.map .node.seen rect { fill: var(--accent-soft); }
.map .node text { font: 500 12px var(--f-mono); fill: var(--ink); }
.map .badge circle { fill: var(--err); }
.map .badge text { font: 600 10px var(--f-mono); fill: #fff; }
.map .scout { fill: var(--accent); }
.log { border-top: 1px solid var(--line); background: var(--code-bg); color: var(--code-ink); font: 400 12.5px/1.65 var(--f-mono); padding: 12px 14px; min-height: 104px; overflow-x: auto; white-space: pre; }
.log .d { color: var(--code-dim); }
.log .x { color: #ff8a78; }
.log .k { color: #7fd6a8; }

/* Proof strip */
.proof { border-bottom: 1px solid var(--line); background: var(--sheet); }
.proof .wrap { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); }
.proof div.cell { padding: 26px 20px 24px; border-left: 1px solid var(--line); }
.proof div.cell:first-child { border-left: 0; padding-left: 0; }
.proof b { display: block; font: 800 30px/1 var(--f-display); font-stretch: 112%; letter-spacing: -.02em; font-variant-numeric: tabular-nums; }
.proof span { display: block; margin-top: 8px; font-size: 14px; color: var(--ink-2); line-height: 1.45; }
@media (max-width: 820px) {
  .proof .wrap { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .proof div.cell:nth-child(3) { border-left: 0; padding-left: 0; }
  .proof div.cell:nth-child(n+3) { border-top: 1px solid var(--line); }
}

/* Sections */
section.band { padding-block: 72px; border-bottom: 1px solid var(--line); }
@media (max-width: 600px) { section.band { padding-block: 48px; } }
.band h2 { font-size: clamp(28px, 3.6vw, 40px); font-weight: 800; font-stretch: 112%; letter-spacing: -.02em; line-height: 1.05; }
.band .intro { color: var(--ink-2); max-width: 40em; margin: 14px 0 0; font-size: 17px; }

.layers { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0; margin-top: 40px; border-top: 2px solid var(--ink); }
.layer { padding: 22px 24px 4px 0; }
.layer + .layer { padding-left: 24px; border-left: 1px solid var(--line); }
.layer .tag { font: 500 12px/1 var(--f-mono); color: var(--accent); letter-spacing: .06em; }
.layer h3 { font-size: 21px; font-weight: 700; font-stretch: 112%; margin-top: 10px; }
.layer p { color: var(--ink-2); margin: 10px 0 0; font-size: 15px; }
.layer ul { margin: 12px 0 0; padding: 0; list-style: none; font-size: 14px; }
.layer li { padding: 7px 0; border-top: 1px dashed var(--line); display: flex; gap: 10px; }
.layer li code { background: none; padding: 0; color: var(--ink); white-space: nowrap; }
@media (max-width: 820px) {
  .layers { grid-template-columns: minmax(0, 1fr); }
  .layer + .layer { padding-left: 0; border-left: 0; border-top: 1px solid var(--line); margin-top: 8px; }
}

.compare { margin-top: 36px; overflow-x: auto; border: 1px solid var(--line); border-radius: 8px; background: var(--sheet); }
.compare table { width: 100%; min-width: 640px; }
.compare td:first-child { color: var(--ink-2); }
.compare th.us, .compare td.us { background: var(--accent-soft); }
.y { color: var(--ok); font-weight: 600; }
.n { color: var(--ink-3); }

/* Chapter index on the landing page */
.chapters { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 0; margin-top: 32px; border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.chapters a { display: grid; grid-template-columns: 32px minmax(0, 1fr); column-gap: 8px; padding: 16px 18px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); text-decoration: none; color: var(--ink); background: var(--sheet); }
.chapters a:hover { background: var(--accent-soft); }
.chapters span { font: 500 12px/1.6 var(--f-mono); color: var(--ink-3); grid-row: span 2; }
.chapters b { font-weight: 600; font-size: 15px; line-height: 1.35; }
.chapters em { font-style: normal; font-size: 13.5px; color: var(--ink-2); margin-top: 4px; }

/* Docs pages: index rail + one chapter */
.manual .wrap { display: grid; grid-template-columns: 230px minmax(0, 1fr); gap: 56px; padding-block: 48px 80px; }
.toc { position: sticky; top: calc(env(safe-area-inset-top, 0px) + 76px); align-self: start; max-height: calc(100vh - 96px); overflow-y: auto; font-size: 14px; }
.toc p { font: 500 11px/1 var(--f-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--ink-3); margin: 18px 0 8px; }
.toc p:first-child { margin-top: 0; }
.toc a { display: block; padding: 4px 0 4px 12px; border-left: 2px solid var(--line); color: var(--ink-2); text-decoration: none; }
.toc a:hover { color: var(--ink); }
.toc a[aria-current=page] { border-left-color: var(--accent); color: var(--ink); font-weight: 600; }
@media (max-width: 920px) {
  .manual .wrap { grid-template-columns: minmax(0, 1fr); gap: 24px; padding-block: 24px 64px; }
  .toc { position: static; max-height: none; display: flex; gap: 6px; overflow-x: auto; padding-bottom: 6px; }
  .toc p { display: none; }
  .toc a { flex: none; border: 1px solid var(--line); border-radius: 999px; padding: 4px 12px; white-space: nowrap; }
  .toc a[aria-current=page] { border-color: var(--accent); }
}

.doc { min-width: 0; max-width: 760px; }
.doc .num { font: 500 12px/1 var(--f-mono); color: var(--ink-3); letter-spacing: .06em; }
.doc h1 { font-size: clamp(30px, 4vw, 40px); font-weight: 800; font-stretch: 112%; letter-spacing: -.02em; line-height: 1.08; margin-top: 10px; }
.doc h2 { font-size: 24px; font-weight: 800; font-stretch: 112%; letter-spacing: -.01em; margin-top: 44px; line-height: 1.15; scroll-margin-top: 72px; }
.doc h3 { font-size: 18px; font-weight: 700; margin-top: 30px; scroll-margin-top: 72px; }
.doc p, .doc li { color: var(--ink-2); }
.doc p { margin: 12px 0 0; }
.doc ul, .doc ol { margin: 12px 0 0; padding-left: 22px; }
.doc li + li { margin-top: 4px; }
.doc li > ul { margin-top: 4px; }
.doc strong { color: var(--ink); }
.doc blockquote { margin: 18px 0 0; padding: 10px 16px; border-left: 3px solid var(--warn); background: color-mix(in srgb, var(--warn) 9%, var(--sheet)); }
.doc blockquote p { margin: 0; }
.doc h2 a.anchor, .doc h3 a.anchor { color: var(--ink-3); text-decoration: none; margin-left: 8px; opacity: 0; font-weight: 400; }
.doc h2:hover a.anchor, .doc h3:hover a.anchor, .doc a.anchor:focus-visible { opacity: 1; }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 56px; padding-top: 20px; border-top: 1px solid var(--line); }
.pager a { display: block; padding: 12px 14px; border: 1px solid var(--line); border-radius: 6px; text-decoration: none; color: var(--ink); background: var(--sheet); min-width: 0; }
.pager a:hover { border-color: var(--accent); }
.pager small { display: block; font: 500 11px/1.4 var(--f-mono); color: var(--ink-3); letter-spacing: .06em; text-transform: uppercase; }
.pager .next { grid-column: 2; text-align: right; }
.edit { margin-top: 16px; font-size: 13px; color: var(--ink-3); }
.edit a { color: var(--ink-3); }

.note { margin-top: 18px; padding: 12px 16px; border-left: 3px solid var(--warn); background: color-mix(in srgb, var(--warn) 9%, var(--sheet)); font-size: 15px; color: var(--ink-2); }
.note b { color: var(--ink); }

pre.code { position: relative; margin: 16px 0 0; background: var(--code-bg); color: var(--code-ink); border-radius: 6px; padding: 14px 16px; font-size: 13px; line-height: 1.6; overflow-x: auto; }
pre.code .c { color: var(--code-dim); }
pre.code .x { color: #ff8a78; }
pre.code .k { color: #7fd6a8; }
pre.code .w { color: #f0c46b; }
.copy { position: absolute; top: 8px; right: 8px; font: 500 11px/1 var(--f-mono); color: var(--code-dim); background: transparent; border: 1px solid #2c3c45; border-radius: 4px; padding: 5px 8px; cursor: pointer; }
.copy:hover { color: var(--code-ink); border-color: var(--code-dim); }

.tbl { margin-top: 16px; overflow-x: auto; border: 1px solid var(--line); border-radius: 6px; background: var(--sheet); }
table { border-collapse: collapse; width: 100%; font-size: 14px; }
th, td { text-align: left; padding: 9px 12px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { font: 500 11.5px/1.3 var(--f-mono); letter-spacing: .05em; text-transform: uppercase; color: var(--ink-3); background: var(--paper); }
tr:last-child td { border-bottom: 0; }
td code { white-space: nowrap; }
.sev { font: 500 12px/1 var(--f-mono); }
.sev.e { color: var(--err); } .sev.w { color: var(--warn); } .sev.i { color: var(--ink-3); }

.tabs { margin-top: 16px; }
.tabs [role=tablist] { display: flex; gap: 4px; border-bottom: 1px solid var(--line); flex-wrap: wrap; }
.tabs [role=tab] { font: 500 14px var(--f-body); background: none; border: 0; border-bottom: 2px solid transparent; padding: 8px 12px; color: var(--ink-2); cursor: pointer; margin-bottom: -1px; }
.tabs [role=tab][aria-selected=true] { color: var(--ink); border-bottom-color: var(--accent); }
.tabs [role=tabpanel] p:first-child { margin-top: 14px; }

footer { padding-block: 32px 48px; color: var(--ink-3); font-size: 14px; }
footer .wrap { display: flex; flex-wrap: wrap; gap: 12px 28px; justify-content: space-between; }
.cmd .copy { position: static; flex: none; }
.chapters a { align-content: start; }

/* What it catches: six defect kinds in a ruled grid */
.catches { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); margin-top: 36px; border-top: 2px solid var(--ink); }
.catches > div { padding: 20px 24px 22px 0; border-bottom: 1px solid var(--line); min-width: 0; }
.catches > div:not(:nth-child(3n + 1)) { padding-left: 24px; border-left: 1px solid var(--line); }
.catches b { font: 700 17px/1.25 var(--f-display); font-stretch: 112%; }
.catches p { margin: 8px 0 0; color: var(--ink-2); font-size: 15px; }
@media (max-width: 820px) {
  .catches { grid-template-columns: minmax(0, 1fr); }
  .catches > div:not(:nth-child(3n + 1)) { padding-left: 0; border-left: 0; }
}

/* Speed: the facts under the timing table */
.facts { list-style: none; padding: 0; margin: 28px 0 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 24px; }
.facts li { color: var(--ink-2); font-size: 15px; min-width: 0; }
.facts b { color: var(--ink); }
@media (max-width: 820px) { .facts { grid-template-columns: minmax(0, 1fr); } }

pre.code.start { max-width: 46em; margin-top: 24px; }