/* ==========================================================================
   GitHub Agentic Workflows — An Interactive Book
   Design system: "Source & Compiled" — authored intent compiles to governed
   infrastructure. Three type voices carry that thesis:
     · Space Grotesk  — display / brand (the product's engineered voice)
     · Source Serif 4 — authored prose (the human "intent" voice, for reading)
     · JetBrains Mono — the compiled / terminal / frontmatter voice
   Palette: cool blueprint paper · ink · iris primary · verified-green · dawn amber.
   ========================================================================== */

:root {
  color-scheme: light dark;
  --paper: #e9edf5;
  --surface: #ffffff;
  --surface-2: #f3f6fc;
  --ink: #161b28;
  --muted: #566076;
  --faint: #8b93a7;
  --line: #d7dde9;
  --line-strong: #c1cadd;
  --iris: #4f46e5;
  --iris-strong: #4035c9;
  --iris-soft: color-mix(in srgb, var(--iris) 12%, transparent);
  --signal: #16794e;
  --signal-bright: #1f9d55;
  --dawn: #c1701a;
  --leader: #0e7c74;
  --warn: #bd4b0e;
  --code-bg: #10162a;
  --code-ink: #e7ecfb;
  --grid: color-mix(in srgb, var(--iris) 7%, transparent);
  --radius: 14px;
  --radius-lg: 24px;
  --sidebar-width: 20rem;
  --shadow: 0 28px 60px -32px rgba(22, 27, 40, 0.5);
  --shadow-sm: 0 12px 30px -20px rgba(22, 27, 40, 0.5);
  --font-display: "Space Grotesk", "Segoe UI", system-ui, -apple-system, sans-serif;
  --font-body: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Consolas, "Liberation Mono", monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #0d1220;
    --surface: #151d2e;
    --surface-2: #1b2439;
    --ink: #e7ecf7;
    --muted: #9aa6bf;
    --faint: #6a748e;
    --line: #263149;
    --line-strong: #33405f;
    --iris: #8f88f8;
    --iris-strong: #aaa5fb;
    --signal: #4ade80;
    --signal-bright: #69e6a0;
    --dawn: #f0b457;
    --leader: #45cfbe;
    --warn: #f0894e;
    --code-bg: #0b1120;
    --shadow: 0 28px 66px -30px rgba(0, 0, 0, 0.66);
    --shadow-sm: 0 12px 34px -22px rgba(0, 0, 0, 0.7);
  }
}

/* ---- base -------------------------------------------------------------- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 18px;
  line-height: 1.7;
  color: var(--ink);
  background-color: var(--paper);
  background-image:
    linear-gradient(to right, var(--grid) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid) 1px, transparent 1px);
  background-size: 38px 38px;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  line-height: 1.08;
  letter-spacing: -0.02em;
  margin: 0 0 0.6em;
  font-weight: 700;
  color: var(--ink);
}
h1 { font-size: clamp(2.4rem, 5.8vw, 4rem); }
h2 { font-size: clamp(1.55rem, 3.4vw, 2.35rem); }
h3 { font-size: 1.3rem; }

p { margin: 0 0 1rem; }
a { color: var(--iris); text-decoration-thickness: 1px; text-underline-offset: 0.16em; }
a:hover { color: var(--iris-strong); }
strong { font-weight: 600; }

:focus-visible {
  outline: 3px solid var(--iris);
  outline-offset: 3px;
  border-radius: 6px;
}
::selection { background: color-mix(in srgb, var(--iris) 26%, transparent); }

.container { width: min(1160px, calc(100% - 2.6rem)); margin-inline: auto; }

.eyebrow {
  font-family: var(--font-mono);
  color: var(--iris);
  font-size: 0.76rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  margin: 0 0 0.85rem;
}
.lead {
  color: var(--muted);
  font-size: clamp(1.12rem, 1.7vw, 1.4rem);
  line-height: 1.6;
  max-width: 64ch;
}

.skip-link {
  position: absolute; left: 1rem; top: 0.75rem; z-index: 40;
  transform: translateY(-160%);
  background: var(--surface); color: var(--ink);
  border: 1px solid var(--line-strong); border-radius: 999px;
  padding: 0.55rem 0.95rem; font-family: var(--font-mono); font-size: 0.82rem;
}
.skip-link:focus { transform: translateY(0); }
.visually-hidden {
  position: absolute !important; width: 1px; height: 1px;
  padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0);
  white-space: nowrap; border: 0;
}

/* ---- home: top bar ----------------------------------------------------- */
.site-header { position: relative; }
.topbar {
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
  padding: 1.15rem 0 0;
}
.brand {
  display: inline-flex; align-items: center; gap: 0.6rem;
  font-family: var(--font-mono); font-weight: 700; font-size: 0.95rem;
  color: var(--ink); text-decoration: none; letter-spacing: -0.01em;
}
.brand-badge {
  display: grid; place-items: center; width: 30px; height: 30px; border-radius: 9px;
  background: linear-gradient(135deg, var(--iris), var(--signal-bright));
  color: #fff; font-weight: 700; font-size: 0.82rem;
}
.topnav { display: flex; gap: 1.4rem; font-family: var(--font-mono); font-size: 0.85rem; }
.topnav a { color: var(--muted); text-decoration: none; }
.topnav a:hover { color: var(--iris); }

/* ---- home: hero -------------------------------------------------------- */
.hero { padding: clamp(2.5rem, 6vw, 5rem) 0 clamp(2rem, 4vw, 3.5rem); }
.hero-title { max-width: 18ch; }
.hero .lead { margin-top: 1.2rem; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 0.8rem; margin-top: 1.8rem; }
.btn {
  font-family: var(--font-mono); font-size: 0.9rem; font-weight: 600;
  display: inline-flex; align-items: center; gap: 0.45rem;
  padding: 0.72rem 1.2rem; border-radius: 999px; text-decoration: none;
  border: 1px solid transparent; transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}
.btn-primary { background: var(--iris); color: #fff; box-shadow: var(--shadow-sm); }
.btn-primary:hover { transform: translateY(-2px); color: #fff; }
.btn-ghost { border-color: var(--line-strong); color: var(--ink); background: var(--surface); }
.btn-ghost:hover { border-color: var(--iris); color: var(--iris); transform: translateY(-2px); }

/* ---- home: the compile diptych (signature) ----------------------------- */
.compile-diptych {
  margin: clamp(2.2rem, 5vw, 3.4rem) 0 0;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: stretch;
  gap: 0.75rem;
}
.dip {
  background: var(--code-bg);
  border: 1px solid color-mix(in srgb, #ffffff 10%, var(--code-bg));
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  min-width: 0;
}
.dip-tab {
  display: flex; align-items: center; gap: 0.5rem;
  font-family: var(--font-mono); font-size: 0.76rem; font-weight: 600;
  color: #aeb8d4; letter-spacing: 0.02em;
  padding: 0.6rem 0.9rem;
  border-bottom: 1px solid rgba(148, 163, 184, 0.2);
  background: rgba(255, 255, 255, 0.03);
}
.dip-tab::before {
  content: ""; width: 9px; height: 9px; border-radius: 3px; background: var(--iris);
}
.dip-out .dip-tab::before { background: var(--signal-bright); }
.dip pre {
  margin: 0; padding: 0.95rem 1.05rem;
  font-family: var(--font-mono); font-size: 0.82rem; line-height: 1.62;
  color: var(--code-ink); overflow-x: auto; white-space: pre; tab-size: 2;
}
.dip .k { color: #8fb6ff; }
.dip .p { color: #c6a2ff; }
.dip .c { color: #7f8bab; }
.dip .g { color: var(--signal-bright); }
.dip .a { color: #ffd08a; }
.dip-seam {
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 0.5rem; padding: 0 0.35rem; text-align: center;
}
.seam-cmd {
  font-family: var(--font-mono); font-size: 0.72rem; font-weight: 600; color: var(--muted);
  writing-mode: vertical-rl; transform: rotate(180deg); letter-spacing: 0.08em;
}
.seam-arrow {
  font-family: var(--font-mono); font-size: 1.6rem; color: var(--iris); line-height: 1;
}
@keyframes dip-in { from { opacity: 0; transform: translateY(12px); } to { opacity: 1; transform: none; } }
@keyframes seam-in { from { opacity: 0; transform: translateX(-6px); } to { opacity: 1; transform: none; } }
.dip-source { animation: dip-in 0.5s ease both; }
.dip-seam { animation: seam-in 0.5s 0.35s ease both; }
.dip-out { animation: dip-in 0.6s 0.5s ease both; }

/* ---- home: track band -------------------------------------------------- */
main.container { padding-bottom: 4rem; }
.reading-guide { margin: clamp(2.5rem, 6vw, 4rem) 0 3rem; }
.reading-guide > h2 { font-size: clamp(1.3rem, 2.5vw, 1.7rem); }
.reading-guide > p { color: var(--muted); max-width: 70ch; }
.track-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem; margin-top: 1.4rem;
}

/* ---- home: parts + chapter rows --------------------------------------- */
.part-block { margin: 0 0 3rem; }
.part-header {
  display: flex; align-items: baseline; gap: 0.9rem; flex-wrap: wrap;
  margin: 2.5rem 0 1.25rem;
  padding-bottom: 0.7rem;
  border-bottom: 1px solid var(--line);
}
.part-header .eyebrow {
  margin: 0; color: var(--faint);
  padding: 0.2rem 0.55rem; border: 1px solid var(--line-strong); border-radius: 999px;
}
.part-header h2 { margin: 0; }
.chapter-grid { display: grid; gap: 0.6rem; }

.chapter-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: border-color 0.15s ease, transform 0.15s ease, box-shadow 0.15s ease;
}
.chapter-card:hover {
  border-color: color-mix(in srgb, var(--iris) 55%, var(--line));
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}
.chapter-card .row-link {
  display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 1.1rem;
  padding: 1rem 1.2rem; text-decoration: none; color: inherit;
}
.chapter-card .ch-num {
  font-family: var(--font-mono); font-size: 1.05rem; font-weight: 700;
  color: var(--iris); font-variant-numeric: tabular-nums;
}
.chapter-card .ch-title { font-family: var(--font-display); font-weight: 600; font-size: 1.16rem; color: var(--ink); display: block; }
.chapter-card .ch-obj { color: var(--muted); font-size: 0.98rem; display: block; margin-top: 0.15rem; }
.chapter-card .ch-go { font-family: var(--font-mono); color: var(--faint); font-size: 1.2rem; transition: transform 0.15s ease, color 0.15s ease; }
.chapter-card:hover .ch-go { color: var(--iris); transform: translateX(4px); }

.pending-note {
  background: var(--iris-soft);
  border: 1px dashed color-mix(in srgb, var(--iris) 50%, var(--line));
  border-radius: var(--radius); color: var(--muted); margin: 0; padding: 1rem 1.15rem;
}

/* ---- chapter page: shell + sidebar ------------------------------------ */
.page-shell { display: grid; grid-template-columns: var(--sidebar-width) minmax(0, 1fr); min-height: 100vh; }
.sidebar { background: var(--surface-2); border-right: 1px solid var(--line); }
.sidebar-inner { position: sticky; top: 0; max-height: 100vh; overflow-y: auto; padding: 1.5rem 1.25rem; }
.site-title {
  display: inline-flex; align-items: center; gap: 0.55rem;
  font-family: var(--font-mono); font-weight: 700; font-size: 0.9rem;
  color: var(--ink); text-decoration: none; margin-bottom: 1.4rem; line-height: 1.3;
}
.site-title::before {
  content: "aw"; display: grid; place-items: center; flex: none;
  width: 26px; height: 26px; border-radius: 8px;
  background: linear-gradient(135deg, var(--iris), var(--signal-bright));
  color: #fff; font-size: 0.72rem; font-weight: 700;
}
.chapter-nav ol { list-style: none; margin: 0; padding: 0; }
.nav-part + .nav-part { margin-top: 1.3rem; }
.nav-part-title {
  font-family: var(--font-mono); color: var(--faint);
  font-size: 0.68rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase;
  margin: 0 0 0.4rem; padding: 0 0.65rem;
}
.chapter-nav a {
  display: flex; align-items: baseline; gap: 0.65rem;
  border-radius: 9px; color: var(--muted); padding: 0.5rem 0.65rem;
  text-decoration: none; font-size: 0.95rem; line-height: 1.35;
  border-left: 2px solid transparent;
}
.chapter-nav a:hover { background: var(--surface); color: var(--ink); }
.chapter-nav a.is-current {
  background: var(--iris-soft); color: var(--iris-strong);
  border-left-color: var(--iris); font-weight: 600;
}
.chapter-number { font-family: var(--font-mono); font-size: 0.8rem; color: var(--faint); font-variant-numeric: tabular-nums; }
.chapter-nav a.is-current .chapter-number { color: var(--iris); }

/* ---- chapter page: header (frontmatter) ------------------------------- */
.content-shell { min-width: 0; }
.chapter-header {
  padding: clamp(2.2rem, 5vw, 4rem) clamp(1.5rem, 5vw, 4.5rem) clamp(1.6rem, 3vw, 2.4rem);
  border-bottom: 1px dashed var(--line-strong);
  position: relative;
}
.chapter-header::after {
  content: "---"; position: absolute; bottom: -0.72rem; left: clamp(1.5rem, 5vw, 4.5rem);
  font-family: var(--font-mono); font-weight: 700; color: var(--faint);
  background: var(--paper); padding-right: 0.6rem; letter-spacing: 0.1em;
}
.breadcrumb { font-family: var(--font-mono); color: var(--faint); font-size: 0.82rem; margin-bottom: 1rem; }
.breadcrumb a { color: var(--muted); text-decoration: none; }
.breadcrumb a:hover { color: var(--iris); }
.fm { font-family: var(--font-mono); font-size: 0.82rem; margin: 0 0 1rem; color: var(--muted); }
.fm .fm-k { color: var(--iris); }
.fm .fm-v { color: var(--ink); }
.fm .fm-sep { color: var(--faint); margin: 0 0.5rem; }
.chapter-header h1 { max-width: 20ch; }
.chapter-header .lead { margin-top: 0.6rem; }

.chapter-main { margin: 0 auto; max-width: 1000px; padding: clamp(1.5rem, 4vw, 3rem) clamp(1.5rem, 5vw, 4.5rem); }

/* meta cards (on this page / features / prerequisites) */
.chapter-meta { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 0.9rem; margin-bottom: 2.5rem; }
.metadata-card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 1rem 1.1rem; }
.metadata-card h2 { font-family: var(--font-mono); font-size: 0.72rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--faint); margin: 0 0 0.7rem; }
.metadata-card ol, .metadata-card ul { margin: 0; padding-left: 1.15rem; font-size: 0.95rem; }
.metadata-card ol { list-style: none; padding-left: 0; counter-reset: toc; }
.metadata-card ol li { counter-increment: toc; padding-left: 1.9rem; position: relative; margin: 0.28rem 0; }
.metadata-card ol li::before {
  content: counter(toc, decimal-leading-zero); position: absolute; left: 0; top: 0.05rem;
  font-family: var(--font-mono); font-size: 0.74rem; color: var(--iris); font-weight: 600;
}
.metadata-card a { text-decoration: none; color: var(--muted); }
.metadata-card a:hover { color: var(--iris); }
.tag-list { display: flex; flex-wrap: wrap; gap: 0.4rem; list-style: none; margin: 0; padding: 0; }
.tag-list li {
  font-family: var(--font-mono); font-size: 0.76rem; color: var(--muted);
  border: 1px solid var(--line); border-radius: 999px; padding: 0.16rem 0.55rem; background: var(--surface-2);
}
.component-list summary { cursor: pointer; font-family: var(--font-mono); color: var(--muted); font-size: 0.85rem; }
.component-list ul { display: flex; flex-wrap: wrap; gap: 0.4rem; list-style: none; margin: 0.6rem 0 0; padding: 0; }
.component-list li { font-family: var(--font-mono); font-size: 0.76rem; color: var(--muted); border: 1px solid var(--line); border-radius: 999px; padding: 0.16rem 0.55rem; }

/* ---- chapter page: sections ------------------------------------------- */
.chapter-section { margin: 0 0 2.75rem; scroll-margin-top: 1.5rem; }
.chapter-section h2 { display: flex; align-items: baseline; gap: 0.6rem; }
.chapter-section h2::before {
  content: "##"; font-family: var(--font-mono); font-weight: 600;
  font-size: 0.72em; color: var(--iris); opacity: 0.65; letter-spacing: 0.02em;
}
.anchor-link { color: inherit; text-decoration: none; }
.anchor-link:hover::after { content: " #"; color: var(--iris); }
.section-content { min-height: 2rem; }

/* reading rhythm for authored prose */
.section-content > :first-child { margin-top: 0; }
.section-content > :last-child { margin-bottom: 0; }
.section-content p, .section-content li { max-width: 74ch; }
.section-content h3 { font-size: 1.25rem; margin: 2rem 0 0.7rem; }
.section-content ul, .section-content ol { padding-left: 1.35rem; }
.section-content li { margin: 0.3rem 0; }
.section-content table { width: 100%; border-collapse: collapse; margin: 1.5rem 0; font-size: 0.94rem; font-family: var(--font-display); }
.section-content th, .section-content td { border: 1px solid var(--line); padding: 0.6rem 0.75rem; text-align: left; vertical-align: top; }
.section-content thead th { background: var(--surface-2); font-family: var(--font-mono); font-size: 0.78rem; letter-spacing: 0.03em; text-transform: uppercase; color: var(--muted); }

/* ---- code -------------------------------------------------------------- */
pre { background: var(--code-bg); border-radius: var(--radius); color: var(--code-ink); overflow-x: auto; padding: 1rem 1.1rem; font-size: 0.9rem; }
code { font-family: var(--font-mono); font-size: 0.92em; }
:not(pre) > code { background: var(--iris-soft); color: var(--iris-strong); border-radius: 5px; padding: 0.08rem 0.32rem; font-size: 0.86em; }
.code-block { position: relative; }
.copy-code {
  position: absolute; right: 0.6rem; top: 0.6rem;
  font-family: var(--font-mono); font-size: 0.74rem;
  background: rgba(255, 255, 255, 0.1); border: 1px solid rgba(255, 255, 255, 0.22);
  border-radius: 999px; color: #e7ecfb; cursor: pointer; padding: 0.24rem 0.62rem;
}
.copy-code:hover { background: rgba(255, 255, 255, 0.2); }

/* captioned code figures — styled as a labelled terminal/file card */
figure.code { position: relative; margin: 1.9rem 0; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; background: var(--code-bg); box-shadow: var(--shadow-sm); }
figure.code > figcaption {
  display: flex; align-items: center; flex-wrap: wrap; gap: 0.5rem;
  padding: 0.62rem 4.75rem 0.62rem 1rem;
  font-family: var(--font-mono); font-size: 0.78rem; font-weight: 600; color: #b9c3dc;
  background: rgba(255, 255, 255, 0.04); border-bottom: 1px solid rgba(148, 163, 184, 0.22);
}
figure.code > figcaption::before { content: "›"; color: var(--signal-bright); font-weight: 700; }
figure.code > pre { margin: 0; border-radius: 0; background: transparent; }
figure.code .copy-code { top: 0.5rem; right: 0.55rem; }
figure.code.needs-secret { border-color: color-mix(in srgb, var(--warn) 55%, var(--line)); }
.code-badge {
  display: inline-flex; align-items: center; gap: 0.3rem;
  font-family: var(--font-mono); font-size: 0.68rem; font-weight: 600; letter-spacing: 0.03em; text-transform: uppercase;
  color: #ffe1c2; background: color-mix(in srgb, var(--warn) 34%, transparent);
  border: 1px solid color-mix(in srgb, var(--warn) 62%, transparent); border-radius: 999px;
  padding: 0.08rem 0.5rem; white-space: nowrap;
}

/* ---- content components: callouts ------------------------------------- */
.callout {
  --c: var(--iris);
  border: 1px solid var(--line); border-left: 3px solid var(--c);
  border-radius: var(--radius);
  background: color-mix(in srgb, var(--c) 6%, var(--surface));
  padding: 1.05rem 1.2rem; margin: 1.6rem 0;
}
.callout > :first-child { margin-top: 0; }
.callout > :last-child { margin-bottom: 0; }
.callout-title {
  display: flex; align-items: center; gap: 0.5rem;
  font-family: var(--font-mono); font-size: 0.74rem; font-weight: 700;
  letter-spacing: 0.06em; text-transform: uppercase; color: var(--c);
  margin: 0 0 0.5rem;
}
.callout-title::before { content: ""; width: 9px; height: 9px; border-radius: 3px; background: var(--c); flex: none; }
.callout--builder { --c: var(--iris); }
.callout--leader  { --c: var(--leader); }
.callout--warning { --c: var(--warn); }
.callout--tip     { --c: var(--signal); }
.callout--note    { --c: var(--muted); }

/* case study — the "measured / impact" moment, warm dawn accent */
.case-study {
  border: 1px solid color-mix(in srgb, var(--dawn) 40%, var(--line)); border-radius: var(--radius);
  background: color-mix(in srgb, var(--dawn) 7%, var(--surface));
  padding: 1.2rem 1.35rem; margin: 1.9rem 0; box-shadow: var(--shadow-sm);
}
.case-study::before {
  content: "◆ Measured"; display: inline-block; font-family: var(--font-mono);
  font-size: 0.68rem; font-weight: 700; letter-spacing: 0.07em; text-transform: uppercase;
  color: var(--dawn); margin-bottom: 0.55rem;
}
.case-study > :last-child { margin-bottom: 0; }
.case-study .case-study-title { font-family: var(--font-display); font-weight: 700; margin: 0 0 0.45rem; font-size: 1.1rem; }

/* "when not to" list */
.when-not { list-style: none; margin: 1.35rem 0; padding: 0; display: grid; gap: 0.5rem; }
.when-not li {
  position: relative; padding: 0.6rem 0.85rem 0.6rem 2.2rem;
  border: 1px solid color-mix(in srgb, var(--warn) 40%, var(--line)); border-radius: 10px;
  background: color-mix(in srgb, var(--warn) 6%, var(--surface)); max-width: none;
}
.when-not li::before { content: "✕"; position: absolute; left: 0.9rem; top: 0.62rem; color: var(--warn); font-weight: 700; font-family: var(--font-mono); }

/* cross-reference links */
a.xref { font-weight: 600; text-decoration: none; border-bottom: 1px dashed color-mix(in srgb, var(--iris) 55%, var(--line)); }
a.xref::before { content: "→ "; color: var(--iris); font-family: var(--font-mono); }
a.xref:hover { border-bottom-style: solid; }

/* ---- pager + footer ---------------------------------------------------- */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; margin: 3rem 0 1rem; }
.pager-link {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 1rem 1.15rem; text-decoration: none; color: var(--ink);
  font-family: var(--font-display); font-weight: 600; transition: border-color 0.15s ease, transform 0.15s ease;
}
.pager-link:hover { border-color: var(--iris); transform: translateY(-2px); }
.pager-link[rel="next"] { text-align: right; }
.pager-link.is-disabled { color: var(--faint); background: transparent; border-style: dashed; }
.site-footer { border-top: 1px solid var(--line); color: var(--muted); margin-top: 3rem; padding: 1.75rem 0; font-family: var(--font-mono); font-size: 0.82rem; }
.site-footer code { background: none; color: var(--iris); padding: 0; }
.chapter-footer { padding: 1.75rem clamp(1.5rem, 5vw, 4.5rem); margin-top: 2rem; }
.sidebar-toggle { display: none; }

/* ---- responsive -------------------------------------------------------- */
@media (max-width: 960px) {
  .compile-diptych { grid-template-columns: 1fr; }
  .dip-seam { flex-direction: row; padding: 0.2rem 0; }
  .seam-cmd { writing-mode: horizontal-tb; transform: none; }
  .seam-arrow { transform: rotate(90deg); }
}
@media (max-width: 860px) {
  body { font-size: 17px; }
  .page-shell { display: block; }
  .topnav { gap: 1rem; }
  .sidebar-toggle {
    display: inline-flex; position: fixed; z-index: 30; right: 1rem; bottom: 1rem;
    background: var(--iris); border: 0; border-radius: 999px; color: #fff; cursor: pointer;
    font-family: var(--font-mono); font-weight: 600; padding: 0.75rem 1.05rem; box-shadow: var(--shadow);
  }
  .sidebar {
    position: fixed; inset: 0 auto 0 0; z-index: 25; width: min(86vw, var(--sidebar-width));
    transform: translateX(-105%); transition: transform 0.2s ease;
  }
  .sidebar.is-open { transform: translateX(0); }
  .chapter-header { padding-top: 3.2rem; }
  .pager { grid-template-columns: 1fr; }
  .pager-link[rel="next"] { text-align: left; }
}
@media (max-width: 560px) {
  .topnav a:not(:last-child) { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; }
}