/* Engineering To Excel
   Layout concept: a drawing sheet. Hairline rules, a left-aligned reading column,
   metadata in title blocks, parts in a bill of materials.
   Light = drafting paper. Dark = blueprint. */

:root {
  --font-display: "Barlow Condensed", "Arial Narrow", "Helvetica Neue", Arial, sans-serif;
  --font-body: "Atkinson Hyperlegible", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;

  --paper: #f3f5f4;
  --paper-2: #e8edec;
  --panel: #fbfcfb;
  --ink: #162231;
  --muted: #53647a;
  --rule: #c5d0d6;
  --grid: #dde5e8;
  --blue: #1b4f9c;
  --blue-soft: #e6eef9;
  --signal: #c2410c;
  --on-signal: #ffffff;
  --ok: #1f7a52;
  --ok-soft: #e3f2ea;
  --warn: #8a5300;
  --warn-soft: #fff0d6;
  --danger: #b42318;
  --danger-soft: #fde7e4;
  --code-bg: #edf1f2;
  --code-fg: #1a2a3a;
  --hl-keyword: #1b4f9c;
  --hl-string: #1f7a52;
  --hl-number: #a35400;
  --hl-comment: #5f7285;
  --hl-title: #7a2e8f;

  --header-h: 64px;
  --measure: 68ch;
  --r: 2px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0c1828;
    --paper-2: #10223a;
    --panel: #112640;
    --ink: #e4ecf5;
    --muted: #9aaec4;
    --rule: #28405f;
    --grid: #15294a;
    --blue: #86b6ff;
    --blue-soft: #13294a;
    --signal: #ff8a4c;
    --on-signal: #1b0e04;
    --ok: #5fd3a0;
    --ok-soft: #0f2d22;
    --warn: #ffc56b;
    --warn-soft: #2e2410;
    --danger: #ff8f85;
    --danger-soft: #33161a;
    --code-bg: #091323;
    --code-fg: #dce7f4;
    --hl-keyword: #86b6ff;
    --hl-string: #7fd8ac;
    --hl-number: #ffc56b;
    --hl-comment: #7f93aa;
    --hl-title: #d6a8ff;
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --paper: #0c1828;
  --paper-2: #10223a;
  --panel: #112640;
  --ink: #e4ecf5;
  --muted: #9aaec4;
  --rule: #28405f;
  --grid: #15294a;
  --blue: #86b6ff;
  --blue-soft: #13294a;
  --signal: #ff8a4c;
  --on-signal: #1b0e04;
  --ok: #5fd3a0;
  --ok-soft: #0f2d22;
  --warn: #ffc56b;
  --warn-soft: #2e2410;
  --danger: #ff8f85;
  --danger-soft: #33161a;
  --code-bg: #091323;
  --code-fg: #dce7f4;
  --hl-keyword: #86b6ff;
  --hl-string: #7fd8ac;
  --hl-number: #ffc56b;
  --hl-comment: #7f93aa;
  --hl-title: #d6a8ff;
  color-scheme: dark;
}

/* ---------- base ---------- */

*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-padding-top: calc(var(--header-h) + 16px); }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img, svg { max-width: 100%; }
a { color: var(--blue); text-underline-offset: 0.18em; text-decoration-thickness: 1px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--signal); outline-offset: 2px; border-radius: var(--r); }
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 600; line-height: 1.08; margin: 0; text-wrap: balance; letter-spacing: 0.005em; }
h1 { font-size: clamp(2.5rem, 6.2vw, 4.25rem); font-weight: 700; letter-spacing: -0.005em; }
h2 { font-size: clamp(1.7rem, 3.4vw, 2.25rem); }
h3 { font-size: 1.4rem; }
p { margin: 0; }
code, pre { font-family: var(--font-mono); }
.muted { color: var(--muted); }
.mono { font-family: var(--font-mono); font-size: 0.78rem; letter-spacing: 0.02em; }
.label, .eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}
.eyebrow { color: var(--blue); margin-bottom: 0.9rem; }
.spacer { height: 2.5rem; }
.skip { position: absolute; left: -999px; top: 0; background: var(--ink); color: var(--paper); padding: 0.6rem 1rem; z-index: 100; }
.skip:focus { left: 0; }

/* One gutter rule everywhere: sections are full-bleed bands, .wrap holds the content. */
.wrap {
  width: 100%;
  max-width: 76rem;
  margin-inline: auto;
  padding-left: max(16px, env(safe-area-inset-left, 0px));
  padding-right: max(16px, env(safe-area-inset-right, 0px));
}
.wrap.narrow > * { max-width: 50rem; }

.band-grid {
  background-color: var(--paper);
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 28px 28px;
  background-position: -1px -1px;
}

/* ---------- buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.72rem 1.25rem;
  background: var(--signal);
  color: var(--on-signal);
  border: 2px solid var(--signal);
  border-radius: var(--r);
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  text-decoration: none;
  line-height: 1;
  cursor: pointer;
}
.btn:hover { filter: brightness(1.06); text-decoration: none; }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--ink); }
.btn-ghost:hover { background: var(--ink); color: var(--paper); filter: none; }
.btn-small { padding: 0.5rem 0.85rem; font-size: 1rem; }
.btn-block { width: 100%; }
.icon-btn {
  display: inline-grid; place-items: center; width: 2.4rem; height: 2.4rem;
  background: transparent; color: var(--ink); border: 1px solid var(--rule); border-radius: var(--r); cursor: pointer;
}
.icon-btn:hover { border-color: var(--ink); }

/* ---------- header / footer ---------- */

/* The fixed strip paints the phone's status-bar inset in the header color so nothing scrolls into it. */
body::before {
  content: "";
  position: fixed;
  inset: 0 0 auto;
  height: env(safe-area-inset-top, 0px);
  background: var(--paper);
  z-index: 40;
}
.site-header {
  position: sticky;
  top: env(safe-area-inset-top, 0px);
  z-index: 30;
  background: var(--paper);
  border-bottom: 1px solid var(--rule);
}
.bar { display: flex; align-items: center; gap: 1.25rem; min-height: var(--header-h); flex-wrap: wrap; padding-block: 0.4rem; }
.brand { display: inline-flex; align-items: center; gap: 0.7rem; color: var(--ink); text-decoration: none; }
.brand .mark { color: var(--ink); flex: none; }
.brand-text { font-family: var(--font-display); font-weight: 700; font-size: 1.15rem; line-height: 0.95; text-transform: uppercase; letter-spacing: 0.06em; }
.main-nav { margin-left: auto; }
.main-nav ul { display: flex; gap: 0.25rem; list-style: none; margin: 0; padding: 0; flex-wrap: wrap; }
.main-nav a {
  display: block; padding: 0.4rem 0.7rem; color: var(--ink); text-decoration: none;
  font-family: var(--font-mono); font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.08em;
  border-bottom: 2px solid transparent;
}
.main-nav a:hover { border-bottom-color: var(--rule); }
.main-nav a[aria-current="page"] { border-bottom-color: var(--signal); }
.bar-actions { display: flex; align-items: center; gap: 0.6rem; }

.preview-bar { background: var(--ink); color: var(--paper); font-family: var(--font-mono); font-size: 0.72rem; letter-spacing: 0.04em; padding-block: 0.45rem; }

.site-footer { margin-top: 4rem; border-top: 1px solid var(--rule); padding-block: 2.5rem 3rem; background: var(--paper-2); }
.foot-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr; gap: 2rem; margin-bottom: 2rem; }
.foot-grid > * { min-width: 0; }
.foot-brand { font-family: var(--font-display); font-size: 1.6rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 0.4rem; }
.plain { list-style: none; margin: 0.6rem 0 0; padding: 0; display: grid; gap: 0.35rem; }
.fine { font-size: 0.85rem; color: var(--muted); max-width: 60ch; margin-top: 0.5rem; }

/* ---------- page heads, sections ---------- */

.page-head { padding-block: 2.5rem 2.25rem; border-bottom: 1px solid var(--rule); }
.page-head .lead { margin-top: 1rem; }
.lead { font-size: 1.2rem; color: var(--muted); max-width: 58ch; }
.crumbs { margin-bottom: 1.4rem; }
.crumbs ol { display: flex; flex-wrap: wrap; gap: 0.3rem 0.5rem; list-style: none; margin: 0; padding: 0; font-family: var(--font-mono); font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.06em; }
.crumbs li + li::before { content: "/"; margin-right: 0.5rem; color: var(--rule); }
.crumbs a { color: var(--muted); }
.crumbs span { color: var(--ink); }

.section { padding-block: 3rem 0.5rem; }
.section.tint { background: var(--paper-2); padding-block: 3rem; margin-top: 3rem; border-block: 1px solid var(--rule); }
.section-head { display: flex; align-items: baseline; justify-content: space-between; gap: 1rem; margin-bottom: 1.4rem; flex-wrap: wrap; }
.more { font-family: var(--font-mono); font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.08em; }

/* ---------- hero ---------- */

.hero { padding-block: 3.5rem 3.5rem; border-bottom: 1px solid var(--rule); }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr); gap: 3rem; align-items: center; }
.hero-copy .lead { margin-top: 1.25rem; }
.actions { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-top: 1.75rem; }

.sheetpanel { background: var(--panel); border: 1px solid var(--ink); padding: 1.4rem 1.4rem 0; position: relative; }
.sheetpanel::before, .sheetpanel::after { content: ""; position: absolute; width: 14px; height: 14px; border: 2px solid var(--signal); }
.sheetpanel::before { top: -2px; left: -2px; border-right: 0; border-bottom: 0; }
.sheetpanel::after { bottom: -2px; right: -2px; border-left: 0; border-top: 0; }
.panel-title { margin-top: 0.4rem; font-size: 2rem; }
.panel-title a { color: var(--ink); text-decoration: none; }
.panel-title a:hover { text-decoration: underline; }
.panel-desc { color: var(--muted); margin-top: 0.6rem; font-size: 0.98rem; }
.mini-parts { list-style: none; margin: 1.1rem 0 1.3rem; padding: 0; border-top: 1px solid var(--rule); }
.mini-parts li { display: flex; gap: 0.8rem; padding: 0.5rem 0; border-bottom: 1px solid var(--rule); font-size: 0.95rem; align-items: baseline; }
.mini-parts li.planned { color: var(--muted); }
.part-no { font-family: var(--font-mono); font-size: 0.75rem; color: var(--blue); flex: none; }

/* ---------- title block ---------- */

.titleblock { display: grid; grid-template-columns: repeat(auto-fit, minmax(7.5rem, 1fr)); margin: 1.75rem 0 0; border: 1px solid var(--ink); background: var(--panel); max-width: 44rem; }
.titleblock > div { padding: 0.55rem 0.85rem 0.65rem; border-right: 1px solid var(--rule); border-bottom: 1px solid var(--rule); margin: 0 -1px -1px 0; min-width: 0; }
.titleblock dt { font-family: var(--font-mono); font-size: 0.66rem; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); }
.titleblock dd { margin: 0.1rem 0 0; font-family: var(--font-display); font-size: 1.3rem; font-weight: 600; line-height: 1.15; }
.titleblock.tight { margin: 0 -1.4rem; max-width: none; border-inline: 0; border-bottom: 0; border-color: var(--rule); background: transparent; }

/* ---------- cards ---------- */

.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 19rem), 1fr)); gap: 1.1rem; }
.card { position: relative; display: flex; flex-direction: column; gap: 0.6rem; padding: 1.1rem 1.2rem 1.15rem; background: var(--panel); border: 1px solid var(--rule); border-radius: var(--r); min-width: 0; }
.card:hover { border-color: var(--ink); }
.card:focus-within { border-color: var(--ink); }
.card-top { display: flex; justify-content: space-between; gap: 0.75rem; align-items: baseline; flex-wrap: wrap; }
.sheet { font-family: var(--font-mono); font-size: 0.72rem; font-weight: 500; letter-spacing: 0.08em; color: var(--blue); }
.card-series { font-family: var(--font-mono); font-size: 0.68rem; color: var(--muted); letter-spacing: 0.03em; }
.card-title { font-size: 1.55rem; }
.card-title a { color: var(--ink); text-decoration: none; }
.card-title a::after { content: ""; position: absolute; inset: 0; }
.card-title a:hover { text-decoration: underline; }
.card-desc { color: var(--muted); font-size: 0.97rem; display: -webkit-box; -webkit-line-clamp: 3; line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.card-meta { display: flex; flex-wrap: wrap; gap: 0.25rem 0.9rem; list-style: none; margin: auto 0 0; padding: 0.7rem 0 0; border-top: 1px solid var(--rule); font-family: var(--font-mono); font-size: 0.74rem; color: var(--muted); }
.chip { display: inline-block; padding: 0.1rem 0.55rem; border: 1px solid var(--rule); border-radius: 999px; font-size: 0.82rem; background: var(--panel); }

/* ---------- features, topics, series rows ---------- */

.features { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(12rem, 1fr)); gap: 1.5rem 2rem; }
.features li { border-top: 2px solid var(--ink); padding-top: 0.8rem; min-width: 0; }
.features p { margin-top: 0.4rem; color: var(--muted); font-size: 0.98rem; }

.topics { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--ink); }
.topic-row { display: grid; grid-template-columns: 4.5rem minmax(0, 16rem) minmax(0, 1fr) auto; gap: 1rem; align-items: baseline; padding: 1rem 0; border-bottom: 1px solid var(--rule); color: var(--ink); text-decoration: none; }
.topic-row:hover { background: var(--paper-2); }
.topic-name { font-family: var(--font-display); font-weight: 600; font-size: 1.5rem; line-height: 1.1; }
.topic-blurb { color: var(--muted); font-size: 0.97rem; }

.series-list { display: grid; gap: 0; border-top: 1px solid var(--ink); }
.series-row { display: grid; grid-template-columns: 4.5rem minmax(0, 1fr) minmax(10rem, 14rem); gap: 1rem 1.25rem; padding: 1.2rem 0; border-bottom: 1px solid var(--rule); color: var(--ink); text-decoration: none; align-items: start; }
.series-row:hover { background: var(--paper-2); }
.series-title { display: block; font-family: var(--font-display); font-weight: 600; font-size: 1.7rem; line-height: 1.1; }
.series-desc { display: block; color: var(--muted); margin-top: 0.3rem; font-size: 0.98rem; }
.series-prog { display: grid; gap: 0.45rem; }
.bar-track { display: block; height: 6px; background: var(--rule); }
.bar-fill { display: block; height: 100%; background: var(--signal); }

.parts { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--ink); }
.part-row { display: grid; grid-template-columns: 2.5rem minmax(0, 1fr) auto; gap: 0.5rem 1rem; padding: 1rem 0.5rem; border-bottom: 1px solid var(--rule); align-items: start; color: var(--ink); text-decoration: none; }
a.part-row:hover { background: var(--paper-2); }
.part-title { display: block; font-family: var(--font-display); font-weight: 600; font-size: 1.35rem; line-height: 1.15; }
.part-sum { display: block; color: var(--muted); font-size: 0.95rem; margin-top: 0.2rem; }
.part-meta { display: grid; justify-items: end; gap: 0.35rem; }
.part.planned .part-title { color: var(--muted); }
.part.current .part-row { background: var(--blue-soft); }
.parts.compact .part-row { grid-template-columns: 2rem minmax(0, 1fr); padding: 0.55rem 0.4rem; }
.parts.compact .part-title { font-size: 1.05rem; font-weight: 600; }
.parts.compact .part-sum, .parts.compact .part-meta { display: none; }
.status { font-family: var(--font-mono); font-size: 0.66rem; text-transform: uppercase; letter-spacing: 0.08em; padding: 0.12rem 0.5rem; border: 1px solid currentColor; white-space: nowrap; }
.status.ok { color: var(--ok); background: var(--ok-soft); }
.status.soon { color: var(--muted); }

/* ---------- library ---------- */

.controls { display: grid; gap: 1.1rem; grid-template-columns: minmax(0, 22rem) 1fr; align-items: start; margin-bottom: 1.4rem; }
.controls .field:nth-child(3) { grid-column: 2; }
.field { display: grid; gap: 0.4rem; min-width: 0; }
.field input[type="search"] { width: 100%; font: inherit; padding: 0.65rem 0.8rem; background: var(--panel); color: var(--ink); border: 1px solid var(--ink); border-radius: var(--r); }
.chips { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.chipbtn { font: inherit; font-size: 0.9rem; padding: 0.35rem 0.8rem; background: var(--panel); color: var(--ink); border: 1px solid var(--rule); border-radius: 999px; cursor: pointer; }
.chipbtn:hover { border-color: var(--ink); }
.chipbtn[aria-pressed="true"] { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.count { margin-bottom: 1rem; font-family: var(--font-mono); font-size: 0.78rem; color: var(--muted); }
.empty { padding: 2rem 0; color: var(--muted); }

/* ---------- tutorial layout ---------- */

.sample-banner { margin: 0 0 1.4rem; padding: 0.7rem 1rem; background: var(--warn-soft); color: var(--ink); border: 1px dashed var(--warn); font-size: 0.95rem; max-width: 52rem; }
.sample-banner b { color: var(--warn); }
.article-layout { display: grid; grid-template-columns: minmax(0, 1fr) 17rem; gap: 3.5rem; padding-block: 2.5rem 0; align-items: start; }
.article { min-width: 0; max-width: 46rem; }
.article > * + * { margin-top: 2rem; }
.side { position: sticky; top: calc(var(--header-h) + 1rem + env(safe-area-inset-top, 0px)); display: grid; gap: 1.5rem; max-height: calc(100vh - var(--header-h) - 2rem); overflow-y: auto; padding-bottom: 1rem; }
.toc summary { cursor: pointer; font-family: var(--font-mono); font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); padding-bottom: 0.6rem; border-bottom: 1px solid var(--ink); }
.toc ul { list-style: none; margin: 0; padding: 0; }
.toc li { border-bottom: 1px solid var(--rule); }
.toc a { display: block; padding: 0.45rem 0.2rem; font-size: 0.93rem; color: var(--ink); text-decoration: none; line-height: 1.3; border-left: 3px solid transparent; padding-left: 0.6rem; }
.toc a:hover { background: var(--paper-2); }
.toc a[aria-current="true"] { border-left-color: var(--signal); font-weight: 700; }
.toc li.l3 a { padding-left: 1.5rem; font-size: 0.88rem; color: var(--muted); }
.side-block .label { margin-bottom: 0.5rem; }

.video { aspect-ratio: 16 / 9; max-width: 100%; background: var(--code-bg); border: 1px solid var(--ink); position: relative; overflow: hidden; }
.video iframe, .video-facade { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.video-facade { background-size: cover; background-position: center; cursor: pointer; padding: 0; }
.play { position: absolute; left: 50%; top: 50%; width: 4.5rem; height: 3.2rem; transform: translate(-50%, -50%); background: var(--signal); border-radius: var(--r); }
.play::after { content: ""; position: absolute; left: 50%; top: 50%; transform: translate(-35%, -50%); border-left: 1.2rem solid var(--on-signal); border-block: 0.8rem solid transparent; }
.videos { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 20rem), 1fr)); gap: 1rem; }
.video-item { margin: 0; display: grid; gap: 0.5rem; min-width: 0; }
.video-item figcaption { display: grid; gap: 0.1rem; font-size: 0.95rem; }
.help .actions { margin-top: 0.4rem; }
.video.placeholder { display: grid; place-content: center; text-align: center; gap: 0.4rem; padding: 1.5rem; color: var(--muted); background-image: linear-gradient(var(--grid) 1px, transparent 1px), linear-gradient(90deg, var(--grid) 1px, transparent 1px); background-size: 28px 28px; }
.video.placeholder code { color: var(--ink); }

.learn { border-top: 2px solid var(--ink); padding-top: 0.9rem; }
.label-h { font-family: var(--font-mono); font-size: 0.72rem; font-weight: 500; text-transform: uppercase; letter-spacing: 0.1em; color: var(--muted); margin-bottom: 0.6rem; }
.learn ul { margin: 0; padding-left: 1.2rem; display: grid; gap: 0.35rem; }

/* Bill of materials */
.bom h2 { margin-bottom: 0.9rem; }
.bom td, .bom th { padding: 0.6rem 0.75rem; }
.aff { font-family: var(--font-mono); font-size: 0.62rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); border: 1px solid var(--rule); padding: 0 0.35rem; margin-left: 0.3rem; }
.tools { margin-top: 0.9rem; display: flex; flex-wrap: wrap; gap: 0.4rem; align-items: center; }
.tools .label { margin-right: 0.3rem; }

.progress { font-family: var(--font-mono); font-size: 0.78rem; color: var(--ok); padding: 0.5rem 0.8rem; background: var(--ok-soft); border: 1px solid var(--ok); }

/* ---------- prose ---------- */

.prose { max-width: var(--measure); min-width: 0; }
.prose > * + * { margin-top: 1.15rem; }
.prose h2 { margin-top: 3rem; padding-top: 0.9rem; border-top: 2px solid var(--ink); scroll-margin-top: calc(var(--header-h) + 1rem); }
.prose h3 { margin-top: 2.2rem; scroll-margin-top: calc(var(--header-h) + 1rem); }
.prose h2 + *, .prose h3 + * { margin-top: 0.8rem; }
.prose .anchor { margin-left: 0.5rem; font-family: var(--font-mono); font-size: 0.6em; color: var(--rule); text-decoration: none; opacity: 0; }
.prose :is(h2, h3):hover .anchor, .prose .anchor:focus-visible { opacity: 1; }
.prose ul, .prose ol { padding-left: 1.4rem; display: grid; gap: 0.4rem; }
.prose li > ul, .prose li > ol { margin-top: 0.4rem; }
.prose :not(pre) > code { font-size: 0.88em; background: var(--code-bg); padding: 0.1em 0.38em; border: 1px solid var(--rule); border-radius: var(--r); }
.prose blockquote { margin-left: 0; padding-left: 1rem; border-left: 3px solid var(--rule); color: var(--muted); }
.prose hr { border: 0; border-top: 1px solid var(--rule); margin-block: 2rem; }
.prose strong { font-weight: 700; }

.prose ul:has(> li > input.task) { list-style: none; padding-left: 0; }
.prose li:has(> input.task) { display: flex; gap: 0.7rem; align-items: baseline; padding: 0.55rem 0.8rem; background: var(--panel); border: 1px solid var(--rule); }
.prose li:has(> input.task:checked) { color: var(--muted); text-decoration: line-through; text-decoration-color: var(--rule); background: transparent; }
.prose input.task { flex: none; width: 1.15rem; height: 1.15rem; accent-color: var(--signal); transform: translateY(0.2rem); cursor: pointer; }

.timestamp { font-family: var(--font-mono); font-size: 0.82em; white-space: nowrap; }
.timestamp::before { content: ""; display: inline-block; margin-right: 0.35em; border-left: 0.5em solid currentColor; border-block: 0.3em solid transparent; }

.figure { margin: 0; }
.figure img { display: block; width: 100%; height: auto; border: 1px solid var(--rule); }
.figure figcaption { margin-top: 0.4rem; font-size: 0.88rem; color: var(--muted); }

/* Tables */
.table-wrap { overflow-x: auto; border: 1px solid var(--ink); background: var(--panel); max-width: 100%; }
table { border-collapse: collapse; width: 100%; font-size: 0.95rem; }
th { text-align: left; font-family: var(--font-mono); font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); border-bottom: 1px solid var(--ink); padding: 0.6rem 0.75rem; background: var(--paper-2); white-space: nowrap; }
td { padding: 0.6rem 0.75rem; border-bottom: 1px solid var(--rule); vertical-align: top; }
tr:last-child td { border-bottom: 0; }
.num { text-align: right; font-variant-numeric: tabular-nums; width: 1%; white-space: nowrap; }
.prose td, .prose th { padding: 0.55rem 0.75rem; }

/* Callouts: a lettered tab on a square-cornered box, not a colored rail. */
.callout { position: relative; margin-top: 1.6rem; padding: 1.1rem 1rem 0.8rem; border: 1px solid; background: var(--panel); }
.callout > p { margin-top: 0.6rem; }
.callout > p:first-of-type { margin-top: 0; }
.callout-label { position: absolute; top: -0.78rem; left: 0.8rem; padding: 0.1rem 0.55rem; font-family: var(--font-mono); font-size: 0.68rem; font-weight: 500; text-transform: uppercase; letter-spacing: 0.1em; color: var(--paper); }
.callout.note { border-color: var(--blue); background: var(--blue-soft); }
.callout.note .callout-label { background: var(--blue); }
.callout.tip { border-color: var(--ok); background: var(--ok-soft); }
.callout.tip .callout-label { background: var(--ok); }
.callout.warning { border-color: var(--warn); background: var(--warn-soft); }
.callout.warning .callout-label { background: var(--warn); }
.callout.danger { border-color: var(--danger); background: var(--danger-soft); }
.callout.danger .callout-label { background: var(--danger); }

/* Code */
.code { margin: 1.4rem 0 0; border: 1px solid var(--ink); background: var(--code-bg); max-width: 100%; min-width: 0; }
.code figcaption { display: flex; justify-content: space-between; align-items: center; gap: 1rem; padding: 0.3rem 0.4rem 0.3rem 0.8rem; border-bottom: 1px solid var(--rule); font-family: var(--font-mono); font-size: 0.7rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); }
.copy { font: inherit; letter-spacing: inherit; text-transform: inherit; padding: 0.3rem 0.7rem; background: transparent; color: var(--ink); border: 1px solid var(--rule); border-radius: var(--r); cursor: pointer; }
.copy:hover { border-color: var(--ink); }
.code pre { margin: 0; padding: 0.9rem 1rem; overflow-x: auto; font-size: 0.86rem; line-height: 1.6; tab-size: 2; }
.code code { color: var(--code-fg); background: none; border: 0; padding: 0; }
.hljs-keyword, .hljs-built_in, .hljs-type, .hljs-literal { color: var(--hl-keyword); }
.hljs-string, .hljs-meta .hljs-string { color: var(--hl-string); }
.hljs-number, .hljs-symbol { color: var(--hl-number); }
.hljs-comment, .hljs-quote { color: var(--hl-comment); font-style: italic; }
.hljs-title, .hljs-title.function_, .hljs-attr { color: var(--hl-title); }
.hljs-meta { color: var(--hl-number); }

/* Pager, related, help */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; }
.pager-cell { display: grid; gap: 0.3rem; padding: 1rem 1.1rem; border: 1px solid var(--ink); background: var(--panel); text-decoration: none; color: var(--ink); min-width: 0; }
a.pager-cell:hover { background: var(--paper-2); }
.pager-cell.next { text-align: right; }
.pager-cell.soon { border-style: dashed; border-color: var(--rule); color: var(--muted); }
.pager-title { font-family: var(--font-display); font-weight: 600; font-size: 1.3rem; line-height: 1.15; }
.help { padding: 1.4rem; border: 1px solid var(--ink); background: var(--panel); display: grid; gap: 0.7rem; justify-items: start; }
.help p { color: var(--muted); max-width: 52ch; }
.related { margin-top: 4rem; }

.cta-band { margin-top: 4rem; background: var(--ink); color: var(--paper); padding-block: 2.5rem; }
.cta-inner { display: flex; justify-content: space-between; align-items: center; gap: 1.5rem; flex-wrap: wrap; }
.cta-inner p { margin-top: 0.4rem; opacity: 0.85; }
.cta-band .btn { border-color: var(--signal); }

/* ---------- responsive ---------- */

@media (max-width: 62rem) {
  .hero-grid { grid-template-columns: minmax(0, 1fr); gap: 2.25rem; }
  .article-layout { grid-template-columns: minmax(0, 1fr); gap: 1.5rem; }
  .side { position: static; max-height: none; overflow: visible; order: -1; }
  .side-block { display: none; }
  .toc { border: 1px solid var(--ink); background: var(--panel); padding: 0.8rem 1rem; }
  .toc[open] summary { margin-bottom: 0.3rem; }
  .foot-grid { grid-template-columns: minmax(0, 1fr); }
  .controls { grid-template-columns: minmax(0, 1fr); }
  .controls .field:nth-child(3) { grid-column: auto; }
}
@media (max-width: 40rem) {
  body { font-size: 1rem; }
  .main-nav { margin-left: 0; order: 3; width: 100%; }
  .bar-actions { margin-left: auto; }
  .topic-row { grid-template-columns: minmax(0, 1fr); gap: 0.2rem; }
  .series-row { grid-template-columns: minmax(0, 1fr); }
  .part-row { grid-template-columns: 2rem minmax(0, 1fr); }
  .part-meta { grid-column: 2; justify-items: start; grid-auto-flow: column; justify-content: start; align-items: center; gap: 0.6rem; }
  .pager { grid-template-columns: minmax(0, 1fr); }
  .pager-cell.next { text-align: left; }
  .hero { padding-block: 2.25rem; }
  .page-head { padding-block: 1.75rem; }
  .cta-inner .btn { width: 100%; }
}

@media (prefers-reduced-motion: no-preference) {
  .btn, .card, .chipbtn, .topic-row, .series-row { transition: background-color 0.15s, border-color 0.15s, color 0.15s, filter 0.15s; }
}

/* ---------- print: people build from a printed page ---------- */
@media print {
  :root { --paper: #fff; --panel: #fff; --paper-2: #f2f2f2; --ink: #000; --muted: #333; --rule: #999; --code-bg: #f6f6f6; --code-fg: #000; }
  body::before, .site-header, .site-footer, .side, .pager, .help, .related, .cta-band, .preview-bar, .copy, .skip, .video, .sample-banner .btn { display: none !important; }
  .band-grid { background: none; }
  .article-layout { display: block; padding-top: 1rem; }
  .article { max-width: none; }
  .code pre { white-space: pre-wrap; overflow: visible; }
  a { color: #000; }
  .prose a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 0.8em; word-break: break-all; }
  .prose h2 { break-after: avoid; }
  .callout, .code, tr { break-inside: avoid; }
}