:root {
  --paper: #f2f3ef;
  --paper-deep: #e6e9e3;
  --ink: #1c2628;
  --ink-soft: #4a5557;
  --grey: #5f6a68;
  --line: #c9cfc9;
  --blue: #2247c9;
  --blue-soft: #e4e9fb;
  --ochre: #8a6400;
  --ochre-soft: #f7edcd;
  --red: #b4432d;
  --red-soft: #f6e2dc;
  --measure: 62ch;
  --gutter: clamp(16px, 5vw, 72px);
}

* { 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-family: "Golos Text", system-ui, sans-serif;
  font-size: 17px;
  line-height: 1.55;
  font-feature-settings: "tnum" 1;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 { font-family: "Piazzolla", Georgia, serif; font-weight: 600; margin: 0; line-height: 1.12; letter-spacing: -0.005em; }
h2 { font-size: clamp(28px, 3.4vw, 40px); max-width: 22ch; margin-bottom: 28px; }
h3 { font-size: 20px; margin-bottom: 8px; }
p { margin: 0 0 1em; max-width: var(--measure); }
a { color: var(--blue); }
a:focus-visible, button:focus-visible { outline: 3px solid var(--ochre); outline-offset: 3px; }

/* header */
.top {
  display: flex; justify-content: space-between; align-items: center; gap: 24px;
  padding: 20px var(--gutter);
  border-bottom: 1px solid var(--line);
}
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; font-weight: 600; font-size: 18px; }
.brand-mark { width: 26px; height: 26px; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linejoin: round; stroke-linecap: round; }
.top-nav { display: flex; gap: 24px; flex-wrap: wrap; }
.top-nav a { color: var(--ink-soft); text-decoration: none; font-size: 15px; }
.top-nav a:hover { color: var(--ink); text-decoration: underline; text-underline-offset: 4px; }

main > section { padding: 72px var(--gutter); border-bottom: 1px solid var(--line); }
main > section:last-child { border-bottom: 0; }

/* hero */
.hero {
  display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  gap: clamp(32px, 5vw, 80px); align-items: start;
  padding-top: 64px;
}
.kicker { color: var(--ink-soft); font-size: 15px; margin-bottom: 20px; }
.hero h1 { font-size: clamp(34px, 4.2vw, 54px); max-width: 16ch; margin-bottom: 24px; }
.lead { font-size: 19px; color: var(--ink-soft); max-width: 52ch; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin: 28px 0 20px; }
.hero-hint { font-size: 14px; color: var(--grey); }

.btn { display: inline-block; padding: 12px 20px; border-radius: 4px; text-decoration: none; font-weight: 500; font-size: 15px; border: 1px solid var(--ink); }
.btn-primary { background: var(--ink); color: var(--paper); }
.btn-primary:hover { background: #2b3a3d; }
.btn-ghost { color: var(--ink); background: transparent; }
.btn-ghost:hover { background: var(--paper-deep); }

/* demo sheet */
.sheet {
  background: #fff; border: 1px solid var(--ink);
  box-shadow: 6px 6px 0 var(--paper-deep);
}
.sheet-head { display: flex; justify-content: space-between; gap: 16px; align-items: flex-start; padding: 20px 22px 14px; border-bottom: 1px solid var(--ink); }
.sheet-title { font-family: "Piazzolla", Georgia, serif; font-weight: 600; font-size: 20px; margin: 0 0 2px; }
.sheet-sub { font-size: 14px; color: var(--ink-soft); margin: 0; }
.tag { font-size: 12px; padding: 4px 8px; border-radius: 3px; white-space: nowrap; }
.tag-example { background: var(--ochre-soft); color: var(--ochre); }

.facts { width: 100%; border-collapse: collapse; }
.facts th, .facts td { padding: 12px 22px; border-bottom: 1px solid var(--line); text-align: left; font-weight: 400; vertical-align: middle; }
.facts th { color: var(--ink-soft); font-size: 15px; width: 55%; }
.facts td { text-align: right; }
.fact {
  font: inherit; font-size: 18px; font-weight: 500; color: var(--blue);
  background: transparent; border: 0; padding: 4px 6px; margin: -4px -6px; cursor: pointer; border-radius: 3px;
  text-decoration: underline; text-decoration-style: dashed; text-decoration-thickness: 1px; text-underline-offset: 5px;
}
.fact:hover { background: var(--blue-soft); }
.fact[aria-pressed="true"] { background: var(--blue); color: #fff; text-decoration: none; }
.fact-gap { color: var(--ochre); white-space: nowrap; font-size: 16px; }
.fact-gap:hover { background: var(--ochre-soft); }
.fact-gap[aria-pressed="true"] { background: var(--ochre); }
.fact-conflict { color: var(--red); }
.fact-conflict:hover { background: var(--red-soft); }
.fact-conflict[aria-pressed="true"] { background: var(--red); }

.source { padding: 18px 22px 20px; background: var(--paper); min-height: 150px; font-size: 15px; }
.source-empty { color: var(--grey); margin: 0; }
.source-doc { font-weight: 600; margin: 0 0 10px; }
.source dl { margin: 0; display: grid; grid-template-columns: max-content 1fr; gap: 4px 16px; }
.source dt { color: var(--ink-soft); }
.source dd { margin: 0; }
.source-note { margin: 12px 0 0; padding-top: 10px; border-top: 1px dashed var(--line); color: var(--ink-soft); }
.source-note.warn { color: var(--ochre); }
.source-note.conflict { color: var(--red); }

/* problem */
.problem-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 32px 48px; max-width: 1000px; }
.problem-item p { color: var(--ink-soft); margin: 0; }

/* steps */
.steps { list-style: none; margin: 0; padding: 0; counter-reset: step; display: grid; grid-template-columns: 1fr; max-width: 760px; }
.steps li { counter-increment: step; display: grid; grid-template-columns: 56px 1fr; gap: 16px; padding: 22px 0; border-top: 1px solid var(--line); }
.steps li::before { grid-row: 1 / span 2; content: counter(step); font-family: "Piazzolla", Georgia, serif; font-size: 34px; line-height: 1; color: var(--blue); font-weight: 500; }
.steps li p { grid-column: 2; margin: 0; color: var(--ink-soft); }

/* brief */
.brief { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr); gap: clamp(32px, 5vw, 80px); align-items: start; }
.brief-list { padding-left: 20px; margin: 0; max-width: var(--measure); }
.brief-list li { margin-bottom: 10px; }
.record { background: #fff; border: 1px solid var(--ink); padding: 22px 24px; font-size: 15px; }
.record-title { font-family: "Piazzolla", Georgia, serif; font-weight: 600; font-size: 19px; margin: 0 0 14px; }
.record dl { margin: 0; }
.record dl > div { display: grid; grid-template-columns: 140px 1fr; gap: 12px; padding: 6px 0; border-top: 1px solid var(--line); }
.record dt { color: var(--ink-soft); }
.record dd { margin: 0; }
.record-note { margin: 14px 0 0; color: var(--ink-soft); font-size: 14px; }

/* rules */
.rules-lead { color: var(--ink-soft); margin-top: -16px; margin-bottom: 36px; }
.rules-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 28px 40px; }
.rule p { margin: 0; }
.rule .rule-no { font-weight: 600; padding-left: 14px; border-left: 3px solid var(--red); margin-bottom: 8px; }
.rule .rule-yes { color: var(--ink-soft); padding-left: 17px; }

/* arch */
.arch-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 32px 40px; margin-bottom: 48px; }
.arch-block p { color: var(--ink-soft); margin: 0; }
.formats { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 32px 40px; padding-top: 32px; border-top: 1px dashed var(--line); max-width: 900px; }
.formats p { color: var(--ink-soft); margin: 0; }

/* pilot */
.pilot-lead { color: var(--ink-soft); margin-top: -16px; margin-bottom: 36px; }
.stages { list-style: none; padding: 0; margin: 0 0 48px; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0; border-top: 2px solid var(--ink); }
.stages li { padding: 18px 20px 18px 0; border-right: 1px solid var(--line); margin-right: 20px; color: var(--ink-soft); font-size: 15px; }
.stages li:last-child { border-right: 0; }
.stages li span { display: block; color: var(--ink); font-family: "Piazzolla", Georgia, serif; font-weight: 600; font-size: 20px; margin-bottom: 8px; }
.stages li:first-child span::after { content: " ✓"; color: var(--blue); }
.accept { max-width: 720px; margin-bottom: 48px; }
.accept ul { padding-left: 20px; margin: 0; color: var(--ink-soft); }
.accept li { margin-bottom: 6px; }
.cta { display: flex; align-items: center; gap: 24px; flex-wrap: wrap; padding: 28px 0 0; border-top: 1px solid var(--line); }
.cta p { margin: 0; font-family: "Piazzolla", Georgia, serif; font-size: 24px; font-weight: 500; }

/* stamp footer */
.stamp {
  margin: 0 var(--gutter) 40px;
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr 1fr 1.4fr 2fr;
  border: 2px solid var(--ink);
}
.stamp-cell { padding: 8px 12px 10px; border-right: 1px solid var(--ink); font-size: 14px; }
.stamp-cell:last-child { border-right: 0; }
.stamp-cell span { display: block; font-size: 11px; color: var(--grey); margin-bottom: 2px; }

/* responsive */
@media (max-width: 1000px) {
  .rules-grid, .arch-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .stages { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .stages li:nth-child(2) { border-right: 0; }
  .stamp { grid-template-columns: repeat(4, 1fr); }
  .stamp-cell { border-bottom: 1px solid var(--ink); }
  .stamp-cell:nth-child(4n) { border-right: 0; }
  .stamp-cell:nth-last-child(-n+3) { border-bottom: 0; }
  .stamp-wide { grid-column: span 2; }
}
@media (max-width: 760px) {
  body { font-size: 16px; }
  main > section { padding: 48px var(--gutter); }
  .hero, .brief { grid-template-columns: 1fr; }
  .hero h1 { font-size: 32px; }
  .lead { font-size: 17px; }
  .problem-grid, .rules-grid, .arch-grid, .formats, .stages { grid-template-columns: 1fr; }
  .stages li { border-right: 0; margin-right: 0; border-bottom: 1px solid var(--line); }
  .top { flex-direction: column; align-items: flex-start; gap: 12px; }
  .top-nav { gap: 16px; }
  .facts th, .facts td { padding: 10px 16px; }
  .sheet-head, .source { padding-left: 16px; padding-right: 16px; }
  .sheet-head { flex-direction: column; }
  .record dl > div { grid-template-columns: 110px 1fr; }
  .stamp { grid-template-columns: 1fr 1fr; }
  .stamp-cell:nth-child(4n) { border-right: 1px solid var(--ink); }
  .stamp-cell:nth-child(2n) { border-right: 0; }
  .stamp-cell:nth-last-child(-n+3) { border-bottom: 1px solid var(--ink); }
  .stamp-cell:last-child { border-bottom: 0; }
  .stamp-wide { grid-column: span 2; }
}