/* Hallmark · macrostructure: Long Document · genre: editorial
 * theme: custom (vibe: "academic paper, magazine touch"
 *   · paper oklch(97.5% 0.006 90) · ink oklch(24% 0.01 80)
 *   · accents #33658A blue / #F26419 orange / #8ED081 green)
 * nav: N6 masthead · footer: Ft4 colophon · enrichment: Tier-A figure + drop cap
 * pre-emit critique: P5 H4 E5 S5 R4 V5 · light-only
 * Aesthetic: an academic paper on screen — front matter, numbered sections,
 * hairline rules, a plated figure, a citation-graph colophon; a magazine touch. */

:root {
  /* ---- neutrals (warm anchor, hue ~85) ---- */
  --color-paper:    oklch(98.5% 0.005 92);   /* warm near-white page */
  --color-paper-2:  oklch(99.2% 0.005 95);   /* plates / cards, brighter */
  --color-paper-3:  oklch(95.2% 0.008 88);   /* sunk panels, code */
  --color-rule:     oklch(89%   0.008 88);   /* hairline */
  --color-rule-2:   oklch(80%   0.010 85);   /* stronger rule */
  --color-neutral:  oklch(47%   0.011 85);   /* faint / captions (AA on paper) */
  --color-muted:    oklch(41%   0.010 82);   /* soft body */
  --color-ink:      oklch(21%   0.011 78);   /* near-black, warm */

  /* ---- brand accents (exact hexes, held as tokens) ---- */
  --color-blue:     #33658A;   /* primary — links, rules, CTA fill */
  --color-orange:   #F26419;   /* spark  — marks, active, arrows, display */
  --color-green:    #8ED081;   /* tree   — diagram markers, tags, prompts */

  --color-accent:      var(--color-blue);
  --color-spark:       var(--color-orange);
  --color-spark-ink:   oklch(47% 0.145 47);            /* orange for small text (AA on paper) */
  --color-tree:        var(--color-green);
  --color-on-accent:   oklch(99% 0.004 95);           /* text on blue fill */
  --color-mark-band:   oklch(87% 0.075 58);           /* orange highlighter */
  --color-blue-soft:   oklch(93% 0.030 250);          /* inline-code / focus wash */
  --color-green-soft:  oklch(93% 0.045 145);          /* tag chip */
  --color-focus:       oklch(52% 0.13 250);

  /* ---- type ---- */
  --display: "Fraunces", "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --serif:   "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, serif;
  --mono:    ui-monospace, "SF Mono", "JetBrains Mono", "Fira Code", Menlo, Consolas, monospace;

  /* ---- spacing (4pt) ---- */
  --space-2xs: 4px;  --space-xs: 8px;  --space-sm: 12px; --space-md: 16px;
  --space-lg: 24px;  --space-xl: 40px; --space-2xl: 64px; --space-3xl: 96px;

  --radius: 4px;
  --maxw: 1080px;
  --measure: 68ch;

  --ease-out: cubic-bezier(0.22, 0.61, 0.36, 1);
  --dur: 480ms;
}

* { box-sizing: border-box; }
html, body { overflow-x: clip; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--color-paper);
  color: var(--color-ink);
  font-family: var(--serif);
  font-size: 18px;
  line-height: 1.65;
  -webkit-font-smoothing: auto;
  text-rendering: optimizeLegibility;
}

a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 2px; text-decoration-thickness: 1px; }
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: 2px;
}

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 var(--space-lg); }

/* magazine highlighter — band sits behind the x-height, never a fat underline */
.hl {
  background-image: linear-gradient(180deg,
    transparent 34%, var(--color-mark-band) 34%,
    var(--color-mark-band) 90%, transparent 90%);
  padding: 0 0.04em;
}

/* ============================================================
   Masthead — journal running head (N6)
   ============================================================ */
.masthead {
  position: sticky; top: 0; z-index: 30;
  background: color-mix(in srgb, var(--color-paper) 90%, transparent);
  backdrop-filter: saturate(1.2) blur(6px);
  border-bottom: 2px solid var(--color-ink);
}
.masthead::after {                   /* the thin second rule of a double rule */
  content: ""; display: block; height: 2px;
  background: var(--color-paper);
  border-bottom: 1px solid var(--color-rule-2);
}
.running-head {
  display: flex; align-items: center; gap: var(--space-lg);
  height: 58px;
}
.wordmark {
  font-family: var(--display);
  font-weight: 600;
  font-size: 22px;
  letter-spacing: 0.01em;
  color: var(--color-ink);
  font-optical-sizing: auto;
}
.wordmark:hover { text-decoration: none; }
.running-head .spacer { flex: 1; }
.masthead-links { display: flex; align-items: baseline; gap: var(--space-lg); }
.masthead-links a {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-muted);
}
.masthead-links a:hover { color: var(--color-accent); text-decoration: none; }

/* ============================================================
   Front matter — the paper's title block (hero)
   ============================================================ */
.frontmatter { padding: var(--space-3xl) 0 var(--space-2xl); }
.eyebrow {
  font-family: var(--mono);
  font-size: 12px; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--color-accent);
  margin: 0 0 var(--space-lg);
}
.title {
  font-family: var(--display);
  font-optical-sizing: auto;
  font-weight: 600;
  font-size: clamp(40px, 6.4vw, 74px);
  line-height: 1.02;
  letter-spacing: -0.015em;
  margin: 0;
  max-width: 18ch;
  overflow-wrap: anywhere; min-width: 0;
}

.frontmatter-body {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: var(--space-2xl);
  align-items: end;
  margin-top: var(--space-xl);
}
.frontmatter-body > * { min-width: 0; }
.abstract {
  font-size: 21px; line-height: 1.55;
  color: var(--color-muted);
  max-width: 46ch; margin: 0;
}
.abstract .label {
  display: block;
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.14em;
  text-transform: uppercase; color: var(--color-neutral);
  margin-bottom: var(--space-xs);
}
.abstract strong { color: var(--color-ink); font-weight: 600; }
.cta-row { display: flex; flex-wrap: wrap; gap: var(--space-sm); align-items: center; margin-top: var(--space-xl); }

/* buttons */
.btn {
  display: inline-flex; align-items: center; gap: var(--space-xs);
  font-family: var(--mono); font-size: 13px; font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1;
  padding: 13px 20px; border-radius: var(--radius);
  border: 1px solid var(--color-rule-2);
  color: var(--color-ink); background: var(--color-paper-2);
  transition: transform 140ms var(--ease-out), border-color 140ms var(--ease-out), color 140ms var(--ease-out);
}
.btn:hover { text-decoration: none; border-color: var(--color-accent); color: var(--color-accent); transform: translateY(-1px); }
.btn:active { transform: translateY(0); }
.btn.primary { background: var(--color-accent); color: var(--color-on-accent); border-color: var(--color-accent); }
.btn.primary:hover { color: var(--color-on-accent); filter: brightness(1.08); }

/* ---- Figure 1 plate (replaces the fake terminal) ---- */
.plate {
  margin: 0;
  min-width: 0;
  background: var(--color-paper-2);
  border: 1px solid var(--color-rule-2);
  border-radius: var(--radius);
  box-shadow: 0 18px 40px -32px rgba(30, 26, 20, 0.45);
  overflow: hidden;
}
.plate .figure-body {
  margin: 0; padding: var(--space-lg) var(--space-lg) var(--space-md);
  font-family: var(--mono); font-size: 12.5px; line-height: 1.6;
  color: var(--color-ink); overflow-x: auto;
}
.plate figcaption {
  border-top: 1px solid var(--color-rule);
  padding: var(--space-sm) var(--space-lg);
  font-family: var(--mono); font-size: 11px; letter-spacing: 0.04em;
  color: var(--color-neutral);
}
.plate figcaption b { color: var(--color-muted); font-weight: 600; }
.f-label  { color: var(--color-accent); }
.f-dim    { color: var(--color-neutral); }
.f-arrow  { color: var(--color-spark); }
.f-tree   { color: color-mix(in srgb, var(--color-green) 72%, var(--color-ink)); }
.f-title  { color: var(--color-ink); font-weight: 600; }

/* ============================================================
   Sections — numbered like a paper
   ============================================================ */
.section { padding: var(--space-2xl) 0; border-top: 1px solid var(--color-rule); }
.section-head { margin-bottom: var(--space-xl); }
.section-num {
  font-family: var(--mono); font-size: 12px; letter-spacing: 0.1em;
  text-transform: uppercase; color: var(--color-accent);
  margin: 0 0 var(--space-sm);
}
.section-head h2 {
  font-family: var(--display); font-optical-sizing: auto;
  font-weight: 600; font-size: clamp(28px, 3.8vw, 40px);
  line-height: 1.08; letter-spacing: -0.01em;
  margin: 0; max-width: 20ch;
  overflow-wrap: anywhere; min-width: 0;
}
.section-head .sub {
  color: var(--color-muted); font-size: 19px;
  max-width: var(--measure); margin: var(--space-md) 0 0;
}
/* drop cap on the lead paragraph of §1 */
.leadin { max-width: var(--measure); font-size: 19px; color: var(--color-muted); margin: 0 0 var(--space-xl); }
.leadin.dropcap::first-letter {
  font-family: var(--display); font-weight: 600;
  float: left; font-size: 3.4em; line-height: 0.78;
  padding: 6px 10px 0 0; color: var(--color-ink);
}

/* feature stack — hairline rows, not an icon-tile grid */
.feature-stack { display: grid; gap: 0; }
.feature {
  display: grid; grid-template-columns: minmax(0, 0.4fr) minmax(0, 1fr);
  gap: var(--space-xl);
  padding: var(--space-xl) 0; border-top: 1px solid var(--color-rule);
}
.feature:last-child { border-bottom: 1px solid var(--color-rule); }
.feature .kicker { font-family: var(--mono); font-size: 12px; color: var(--color-neutral); letter-spacing: 0.04em; }
.feature h3 { font-family: var(--display); font-weight: 600; font-size: 23px; margin: 0 0 var(--space-sm); }
.feature p { color: var(--color-muted); font-size: 17px; margin: 0; max-width: 56ch; }
.feature code { font-family: var(--mono); font-size: 0.82em; background: var(--color-blue-soft);
  color: color-mix(in srgb, var(--color-blue) 70%, var(--color-ink)); padding: 1px 5px; border-radius: 3px; }

/* pull quote — magazine touch */
.pullquote {
  border: none; margin: var(--space-2xl) 0; padding: 0;
  max-width: 22ch;
}
.pullquote p {
  font-family: var(--display); font-optical-sizing: auto;
  font-weight: 500; font-size: clamp(26px, 4vw, 40px);
  line-height: 1.14; color: var(--color-ink); margin: 0;
  border-left: 3px solid var(--color-spark);
  padding-left: var(--space-lg);
}

/* how-it-works — big serif numerals */
.steps { display: grid; gap: 0; }
.step {
  display: grid; grid-template-columns: 72px 1fr; gap: var(--space-lg);
  padding: var(--space-xl) 0; border-top: 1px solid var(--color-rule); align-items: start;
}
.step:last-child { border-bottom: 1px solid var(--color-rule); }
.step .n {
  font-family: var(--display); font-optical-sizing: auto;
  font-weight: 500; font-size: 46px; line-height: 0.9;
  color: var(--color-accent);
}
.step h3 { font-family: var(--display); font-weight: 600; margin: 0 0 var(--space-xs); font-size: 22px; }
.step p { margin: 0; color: var(--color-muted); font-size: 17px; max-width: 62ch; }
.step strong { color: var(--color-ink); }

/* install — inline set command, no terminal */
.setcmd {
  display: flex; align-items: center; gap: var(--space-md); flex-wrap: wrap;
  background: var(--color-paper-3);
  border: 1px solid var(--color-rule-2);
  border-radius: var(--radius);
  padding: 6px 6px 6px var(--space-lg);
  max-width: 100%;
}
.setcmd .cmd { font-family: var(--mono); font-size: 15px; color: var(--color-ink); }
.setcmd .cmd .prompt { color: var(--color-accent); user-select: none; }
.setcmd .spacer { flex: 1; }
.setcmd button {
  font-family: var(--mono); font-size: 12px; font-weight: 600; cursor: pointer;
  color: var(--color-ink); background: var(--color-paper-2);
  border: 1px solid var(--color-rule-2); padding: 9px 14px; border-radius: 3px;
  transition: border-color 140ms var(--ease-out), color 140ms var(--ease-out);
}
.setcmd button:hover { border-color: var(--color-spark); color: var(--color-spark-ink); }

/* ============================================================
   Examples gallery (examples.html)
   ============================================================ */
.gallery { display: grid; gap: 0; }
.example-card {
  display: grid; grid-template-columns: minmax(0, 0.32fr) minmax(0, 1fr);
  gap: var(--space-xl); align-items: baseline;
  padding: var(--space-xl) 0; border-top: 1px solid var(--color-rule); color: inherit;
  transition: background 140ms var(--ease-out);
}
.gallery .example-card:last-child { border-bottom: 1px solid var(--color-rule); }
.example-card:hover { text-decoration: none; background: var(--color-paper-2); }
.example-card:hover h3 { color: var(--color-accent); }
.example-card .repo { font-family: var(--mono); font-size: 12px; color: var(--color-neutral); margin: 0; letter-spacing: 0.03em; }
.example-card h3 { font-family: var(--display); font-weight: 600; margin: 0 0 var(--space-xs); font-size: 24px; transition: color 140ms var(--ease-out); }
.example-card p { margin: 0 0 var(--space-md); color: var(--color-muted); font-size: 17px; max-width: 60ch; }
.example-card .meta { font-family: var(--mono); font-size: 12px; color: var(--color-spark-ink); letter-spacing: 0.03em; }
.gallery-empty {
  border: 1px dashed var(--color-rule-2); border-radius: var(--radius);
  padding: var(--space-3xl) var(--space-xl); text-align: center; color: var(--color-neutral);
  font-family: var(--mono); font-size: 14px;
}

/* ============================================================
   Colophon footer (Ft4)
   ============================================================ */
.colophon {
  border-top: 2px solid var(--color-ink);
  margin-top: var(--space-2xl);
  padding: var(--space-2xl) 0 var(--space-3xl);
}
.colophon .wrap { display: grid; gap: var(--space-lg); grid-template-columns: minmax(0, 1fr) auto; align-items: start; }
.colophon .imprint .wordmark { font-size: 20px; }
.colophon .imprint p { margin: var(--space-xs) 0 0; color: var(--color-muted); font-size: 15px; max-width: 44ch; }
.colophon .links { display: flex; flex-direction: column; gap: var(--space-xs); text-align: right; }
.colophon .links a { font-family: var(--mono); font-size: 12px; letter-spacing: 0.05em; text-transform: uppercase; color: var(--color-muted); }
.colophon .links a:hover { color: var(--color-accent); text-decoration: none; }

/* ============================================================
   Reveal (one quiet entrance)
   ============================================================ */
.reveal { opacity: 0; transform: translateY(12px); }
.reveal.in { opacity: 1; transform: none; transition: opacity var(--dur) var(--ease-out), transform var(--dur) var(--ease-out); }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; }
  .reveal.in { transition: opacity 150ms linear; }
  .btn, .example-card, .setcmd button { transition: none; }
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 860px) {
  body { font-size: 17px; }
  .frontmatter { padding: var(--space-2xl) 0 var(--space-xl); }
  .frontmatter-body { grid-template-columns: minmax(0, 1fr); gap: var(--space-xl); align-items: stretch; }
  .feature { grid-template-columns: minmax(0, 1fr); gap: var(--space-sm); }
  .example-card { grid-template-columns: minmax(0, 1fr); gap: var(--space-sm); }
  .colophon .wrap { grid-template-columns: 1fr; }
  .colophon .links { flex-direction: row; flex-wrap: wrap; gap: var(--space-lg); text-align: left; }
}
@media (max-width: 520px) {
  .running-head { gap: var(--space-md); height: 54px; }
  .masthead-links { gap: var(--space-md); }
  .masthead-links a.hide-sm { display: none; }
  .step { grid-template-columns: 52px 1fr; gap: var(--space-md); }
  .step .n { font-size: 36px; }
}