:root {
  --color-surface: #f6f5f5;
  --color-surface-alt: #eeecec;
  --color-surface-deep: #e2e0df;
  --color-ink: #4c453e;
  --color-ink-soft: #72695f;
  --color-ink-muted: #8a8075;
  --color-line: #d7d5d4;
  --color-primary: #916e45;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e8e2dc;
  --color-accent: #2c0ff0;
  --color-accent-ink: #ffffff;
  --color-highlight: #d2ccf4;
  --color-focus: #2202fd;
  --color-contrast-surface: #241f1a;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #4f4b46;
  --color-contrast-accent: #8474f6;
  --overlay-scrim: linear-gradient(180deg, rgba(36, 31, 26, 0.35) 0%, rgba(36, 31, 26, 0.72) 55%, rgba(36, 31, 26, 0.92) 100%);
  --font-heading: "Songti SC", "Source Han Serif SC", "Noto Serif SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 10.7px;
  --text-sm: 13.4px;
  --text-base: 15px;
  --text-lg: 18.8px;
  --text-xl: 23.4px;
  --text-2xl: 29.3px;
  --text-3xl: 36.6px;
  --text-4xl: 45.8px;
  --text-display: clamp(34px, 5.8vw, 74px);
  --text-figure: clamp(28px, 4.1vw, 53px);
  --weight-heading: 628;
  --weight-body: 400;
  --leading-body: 1.65;
  --leading-heading: 1.27;
  --tracking-heading: 0.007em;
  --radius-sm: 2px;
  --radius-md: 2px;
  --radius-lg: 3px;
  --radius-pill: 3px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 1px 0 rgba(76, 69, 62, 0.12);
  --shadow-2: 0 2px 0 rgba(76, 69, 62, 0.18);
  --space-1: 6px;
  --space-2: 12px;
  --space-3: 18px;
  --space-4: 24px;
  --space-6: 36px;
  --space-8: 48px;
  --container: 1200px;
  --measure: 69ch;
  --gutter: 24px;
  --section-y: 68px;
  --section-y-lg: 95px;
}

/* ============================================================
   reset
   ============================================================ */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 92px;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-3);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

p { margin: 0 0 var(--space-3); }
p:last-child { margin-bottom: 0; }

ul, ol { margin: 0 0 var(--space-3); padding-inline-start: 1.2em; }
li { margin-bottom: var(--space-1); }

a { color: var(--color-primary); text-decoration: none; }
a:hover { color: color-mix(in srgb, var(--color-primary) 78%, var(--color-ink)); }

img, svg, video { max-width: 100%; height: auto; display: block; }

button, input, select, textarea { font: inherit; color: inherit; }

hr { border: 0; height: 1px; background-color: var(--color-line); margin: var(--space-4) 0; }

table { border-collapse: collapse; width: 100%; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

::selection { background: var(--color-highlight); color: var(--color-ink); }

/* ============================================================
   layout primitives
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-6); }

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--gutter);
}

.rule {
  height: 1px;
  width: 100%;
  background-color: var(--color-line);
  border: 0;
  margin: 0;
}

.stack > * + * { margin-top: var(--space-2); }
.cluster { display: flex; flex-wrap: wrap; align-items: center; gap: var(--space-2); }

.is-dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.is-dark h1,
.is-dark h2,
.is-dark h3,
.is-dark h4,
.is-dark h5,
.is-dark h6 { color: var(--color-contrast-ink); }
.is-dark a { color: var(--color-contrast-accent); }
.is-dark a:hover { color: color-mix(in srgb, var(--color-contrast-accent) 70%, var(--color-contrast-ink)); }
.is-dark hr,
.is-dark .rule { background-color: var(--color-contrast-line); }

/* ============================================================
   typography utilities
   ============================================================ */
.t-display {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.03;
  letter-spacing: -0.012em;
  margin: 0;
}

.t-figure {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.02em;
  margin: 0;
  font-variant-numeric: tabular-nums;
}

.t-4xl { font-family: var(--font-heading); font-size: var(--text-4xl); line-height: var(--leading-heading); margin: 0; }
.t-3xl { font-family: var(--font-heading); font-size: var(--text-3xl); line-height: var(--leading-heading); margin: 0; }
.t-2xl { font-family: var(--font-heading); font-size: var(--text-2xl); line-height: var(--leading-heading); margin: 0; }
.t-xl { font-family: var(--font-heading); font-size: var(--text-xl); line-height: var(--leading-heading); margin: 0; }
.t-lg { font-size: var(--text-lg); }
.t-sm { font-size: var(--text-sm); }
.t-xs { font-size: var(--text-xs); }

.num,
[data-num] {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.01em;
}

.unit {
  font-family: var(--font-body);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  margin-inline-start: 2px;
}

.is-dark .unit { color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent); }

.hl { background: linear-gradient(transparent 60%, var(--color-highlight) 60%); }
.u-accent {
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
}
.u-primary {
  text-decoration: underline;
  text-decoration-color: var(--color-primary);
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
}

.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
}
.prose h2 { font-size: var(--text-2xl); margin-top: var(--space-6); }
.prose h3 { font-size: var(--text-xl); margin-top: var(--space-4); }
.prose a {
  text-decoration: underline;
  text-decoration-color: color-mix(in srgb, var(--color-primary) 48%, transparent);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}
.prose a:hover { text-decoration-color: var(--color-primary); }

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding-bottom: var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-line);
  margin-bottom: var(--space-4);
}
.section-head__title { margin: 0; font-size: var(--text-2xl); }
.section-head__meta {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  padding-block: var(--space-2);
  margin: 0;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  list-style: none;
  padding-inline-start: 0;
}
.crumbs li { margin: 0; }
.crumbs__sep { color: var(--color-ink-muted); }
.crumbs a { color: var(--color-ink-soft); }
.crumbs a:hover { color: var(--color-primary); }

/* ============================================================
   buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 9px var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface-alt);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 500;
  line-height: 1.2;
  letter-spacing: 0.02em;
  text-decoration: none;
  cursor: pointer;
  transition: background-color 140ms linear, color 140ms linear, border-color 140ms linear;
}
.btn:hover { border-color: var(--color-primary); color: var(--color-primary); }

.btn--primary {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface));
  color: var(--color-primary-ink);
}

.btn--accent {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}
.btn--accent:hover {
  background-color: color-mix(in srgb, var(--color-accent) 86%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-accent) 86%, var(--color-contrast-surface));
  color: var(--color-accent-ink);
}

.btn--ghost { background-color: transparent; color: var(--color-ink-soft); }

.btn--sm { padding: 6px var(--space-2); font-size: var(--text-xs); }

.copy-btn {
  padding: 2px var(--space-1);
  margin-inline-start: var(--space-1);
  background-color: transparent;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  color: inherit;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: border-color 140ms linear, color 140ms linear;
}
.copy-btn:hover { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }
.copy-btn[data-copy-state="done"] { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }
.copy-note {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
  margin-inline-start: var(--space-1);
}

/* ============================================================
   tags / index furniture
   ============================================================ */
.tag {
  display: inline-block;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  background-color: var(--tag-color, var(--color-primary));
  color: var(--color-primary-ink);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  line-height: 1.7;
  letter-spacing: 0.05em;
  white-space: nowrap;
}
.tag--c1 { --tag-color: var(--color-primary); }
.tag--c2 { --tag-color: var(--color-accent); }
.tag--c3 { --tag-color: var(--color-contrast-accent); }
.tag--c4 { --tag-color: color-mix(in srgb, var(--color-primary) 52%, var(--color-accent)); }
.tag--ghost {
  background-color: transparent;
  color: var(--color-ink-soft);
  border: var(--border-thin) solid var(--color-line);
}

.idx {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface);
  overflow: hidden;
}
.idx__head,
.idx__row {
  display: grid;
  grid-template-columns: var(--idx-cols, 58px minmax(140px, 1.5fr) minmax(120px, 1.2fr) minmax(110px, 1fr) 104px);
  gap: var(--space-3);
  align-items: center;
  padding-inline: var(--space-3);
}
.idx__head {
  min-height: 36px;
  background-color: var(--color-surface-alt);
  border-bottom: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}
.idx__row {
  min-height: 40px;
  border-bottom: var(--border-thin) solid var(--color-line);
  font-size: var(--text-sm);
  transition: background-color 140ms linear;
}
.idx__row:nth-child(odd) { background-color: var(--color-surface); }
.idx__row:nth-child(even) { background-color: var(--color-surface-alt); }
.idx__row:last-child { border-bottom: 0; }
.idx__row:hover { background-color: var(--color-primary-soft); }
.idx__cell { min-width: 0; overflow-wrap: anywhere; }
.idx__cell--no { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-ink-muted); }
.idx__cell--key { font-family: var(--font-mono); color: var(--color-ink); }
.idx__cell--go { text-align: right; }

.entry {
  display: grid;
  grid-template-columns: 74px minmax(0, 1fr);
  gap: var(--space-3);
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface);
  transition: border-color 140ms linear, background-color 140ms linear;
}
.entry + .entry { margin-top: var(--space-2); }
.entry:hover { border-color: var(--color-primary); background-color: color-mix(in srgb, var(--color-primary-soft) 55%, var(--color-surface)); }
.entry__no {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
}
.entry__no::before {
  content: "";
  display: inline-block;
  width: 9px;
  height: 9px;
  margin-inline-end: 6px;
  border-radius: 1px;
  background-color: var(--tag-color, var(--color-line));
}
.entry:hover .entry__no { color: var(--color-primary); }
.entry__title {
  margin: 0 0 var(--space-1);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
}
.entry__desc { margin: 0; font-size: var(--text-sm); color: var(--color-ink-soft); }

.correction-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-inline-start-width: 3px;
  border-inline-start-color: var(--color-accent);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface-alt);
  font-size: var(--text-sm);
}
.correction-bar__text { margin: 0; color: var(--color-ink-soft); }

.filters { display: flex; flex-wrap: wrap; gap: var(--space-1); }
.filter {
  padding: 6px var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface);
  color: var(--color-ink-soft);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: background-color 140ms linear, color 140ms linear, border-color 140ms linear;
}
.filter:hover { border-color: var(--color-primary); color: var(--color-primary); }
.filter[aria-pressed="true"] {
  background-color: var(--color-contrast-surface);
  border-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.qa {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface);
  overflow: hidden;
}
.qa__item { border-bottom: var(--border-thin) solid var(--color-line); }
.qa__item:last-child { border-bottom: 0; }
.qa__trigger {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  width: 100%;
  padding: var(--space-3);
  border: 0;
  background-color: transparent;
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  text-align: left;
  cursor: pointer;
  transition: background-color 140ms linear, color 140ms linear;
}
.qa__trigger:hover { background-color: var(--color-surface-alt); color: var(--color-primary); }
.qa__no {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}
.qa__item.is-open .qa__trigger { background-color: var(--color-surface-alt); color: var(--color-accent); }
.qa__item.is-open .qa__no { color: var(--color-accent); }
.qa__panel { max-height: 0; overflow: hidden; transition: max-height 180ms ease; }
.qa__panel-inner {
  padding: 0 var(--space-3) var(--space-3) calc(var(--space-3) + 46px);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

.data-band {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-sm);
  padding: var(--space-6) var(--space-4);
}
.data-band__num {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 600;
  line-height: 1;
  color: var(--color-contrast-accent);
  font-variant-numeric: tabular-nums;
}
.data-band__label {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
  margin: var(--space-1) 0 0;
}

/* ============================================================
   image frames (page stage consumes)
   ============================================================ */
.frame {
  position: relative;
  display: block;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface-alt);
  margin: 0;
}
.frame > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.frame--3x2 { aspect-ratio: 3 / 2; }
.frame--4x5 { aspect-ratio: 4 / 5; }
.frame--16x9 { aspect-ratio: 16 / 9; }
.frame--dark {
  background-color: var(--color-contrast-surface);
  border-color: var(--color-contrast-line);
}
.frame__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
}
.frame__overlay {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  padding: var(--space-3);
  color: var(--color-contrast-ink);
  z-index: 2;
}
.frame__caption {
  margin: var(--space-1) 0 0;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

/* ============================================================
   rail (page stage consumes)
   ============================================================ */
.rail {
  width: 96px;
  flex: 0 0 96px;
  border-inline-end: var(--border-thin) solid var(--color-line);
  background-color: var(--color-surface-alt);
}
.rail__inner {
  position: sticky;
  top: calc(var(--space-8) + var(--space-3));
  padding: var(--space-3) var(--space-2);
}
.rail__item {
  display: block;
  padding: 6px 4px;
  border-inline-start: 2px solid transparent;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
  transition: color 140ms linear, border-color 140ms linear, background-color 140ms linear;
}
.rail__item:hover { color: var(--color-primary); }
.rail__item.is-active {
  color: var(--color-accent);
  border-inline-start-color: var(--color-accent);
  background-color: var(--color-primary-soft);
}

/* ============================================================
   reveal / to-top / skip link
   ============================================================ */
[data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 200ms linear, transform 200ms ease;
}
[data-reveal].is-in { opacity: 1; transform: none; }

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -120px;
  z-index: 120;
  padding: var(--space-2) var(--space-3);
  background-color: var(--color-accent);
  color: var(--color-accent-ink);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  transition: top 140ms linear;
}
.skip-link:focus { top: var(--space-2); color: var(--color-accent-ink); }

.to-top {
  position: fixed;
  right: var(--space-4);
  bottom: var(--space-4);
  z-index: 90;
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 9px var(--space-3);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 160ms linear, transform 160ms ease, visibility 160ms linear;
}
.to-top.is-visible { opacity: 1; visibility: visible; transform: none; }
.to-top:hover { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }

/* ============================================================
   header
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.header-progress {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  background-color: var(--color-contrast-accent);
  transform: scaleX(0);
  transform-origin: 0 50%;
  pointer-events: none;
}

.site-header__inner {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  min-height: 66px;
  padding-block: var(--space-2);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  flex: 0 0 auto;
  color: var(--color-contrast-ink);
}
.brand:hover { color: var(--color-contrast-ink); }
.brand__mark {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: var(--radius-sm);
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  line-height: 1;
}
.brand__text { display: flex; flex-direction: column; line-height: 1.15; }
.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
}
.brand__line {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}

.header-facts {
  display: flex;
  align-items: baseline;
  gap: var(--space-3);
  margin: 0;
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent);
}
.header-fact { display: inline-flex; align-items: baseline; gap: 4px; white-space: nowrap; }
.header-fact__num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-contrast-accent);
  font-variant-numeric: tabular-nums;
}

.site-nav { margin-inline-start: auto; }
.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  padding: 0;
  list-style: none;
}
.site-nav__item { margin: 0; }
.site-nav__link {
  display: inline-flex;
  align-items: baseline;
  gap: 5px;
  padding: 7px var(--space-2);
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 88%, transparent);
  font-size: var(--text-sm);
  transition: background-color 140ms linear, color 140ms linear, border-color 140ms linear;
}
.site-nav__link:hover {
  background-color: color-mix(in srgb, var(--color-contrast-ink) 10%, transparent);
  color: var(--color-contrast-ink);
}
.site-nav__no {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
  font-variant-numeric: tabular-nums;
}
.site-nav__link[aria-current="page"] {
  background-color: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-primary-ink);
}
.site-nav__link[aria-current="page"] .site-nav__no { color: var(--color-primary-ink); }

.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex: 0 0 auto;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 7px var(--space-2);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  cursor: pointer;
  transition: background-color 140ms linear, color 140ms linear, border-color 140ms linear;
}
.nav-toggle:hover { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }
.nav-toggle[aria-expanded="true"] {
  background-color: var(--color-contrast-ink);
  border-color: var(--color-contrast-ink);
  color: var(--color-contrast-surface);
}
.nav-toggle__grid {
  display: grid;
  grid-template-columns: repeat(2, 4px);
  grid-template-rows: repeat(2, 4px);
  gap: 2px;
}
.nav-toggle__grid i { display: block; width: 4px; height: 4px; background-color: currentColor; }
.nav-toggle__label { line-height: 1; }

/* condensed header on scroll (desktop only) */
@media (min-width: 961px) {
  .site-header.is-condensed .site-header__inner { min-height: 50px; padding-block: var(--space-1); }
  .site-header.is-condensed .brand__line { display: none; }
  .site-header.is-condensed .header-facts { display: none; }
  .site-header.is-condensed .brand__mark { width: 24px; height: 24px; }
}

/* ============================================================
   footer
   ============================================================ */
.site-footer {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  padding-block: var(--section-y-lg) var(--space-6);
}

.footer-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  margin-bottom: var(--space-6);
}
.footer-eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  color: var(--color-contrast-accent);
}
.footer-tagline {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--space-4);
  padding-block: var(--space-6);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}
.footer-col { grid-column: span 2; }
.footer-col--contact { grid-column: span 4; }
.footer-col__title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 500;
  letter-spacing: 0.18em;
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
}
.footer-links { margin: 0; padding: 0; list-style: none; }
.footer-links li { margin-bottom: var(--space-1); }
.footer-link {
  color: color-mix(in srgb, var(--color-contrast-ink) 86%, transparent);
  font-size: var(--text-sm);
  transition: color 140ms linear;
}
.footer-link:hover {
  color: var(--color-contrast-accent);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}
.footer-link--strong {
  color: var(--color-contrast-accent);
  font-family: var(--font-body);
  letter-spacing: 0.02em;
}

.footer-contact__line {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0 var(--space-1);
  margin: 0 0 var(--space-1);
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 86%, transparent);
}
.footer-contact__k {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 48%, transparent);
}
.footer-contact__v { overflow-wrap: anywhere; }
.footer-contact__note {
  margin: var(--space-2) 0 var(--space-2);
  font-size: var(--text-xs);
  line-height: var(--leading-body);
  color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent);
}

.footer-wordmark {
  margin: var(--space-6) 0 var(--space-4);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: calc(var(--text-display) * 1.75);
  line-height: 0.9;
  letter-spacing: -0.03em;
  color: color-mix(in srgb, var(--color-contrast-ink) 88%, var(--color-contrast-accent));
  white-space: nowrap;
  overflow: hidden;
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}
.footer-legal { margin: 0; }
.footer-bottom__links { margin: 0; display: inline-flex; flex-wrap: wrap; align-items: baseline; gap: var(--space-1); }
.footer-bottom__sep { color: color-mix(in srgb, var(--color-contrast-ink) 32%, transparent); }

/* ============================================================
   responsive
   ============================================================ */
@media (max-width: 1024px) {
  .header-facts { display: none; }
  .footer-col { grid-column: span 3; }
  .footer-col--contact { grid-column: span 6; }
}

@media (max-width: 960px) {
  .nav-toggle { display: inline-flex; }

  .site-nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: min(340px, 88vw);
    margin: 0;
    padding: calc(var(--space-8) + var(--space-4)) var(--space-4) var(--space-6);
    background-color: var(--color-contrast-surface);
    border-inline-start: var(--border-thin) solid var(--color-contrast-line);
    overflow-y: auto;
    z-index: 110;
    visibility: hidden;
    transform: translateX(101%);
    transition: transform 200ms ease, visibility 200ms linear;
  }
  .site-nav[data-open] { visibility: visible; transform: none; }

  .site-nav__list { flex-direction: column; align-items: stretch; gap: 0; }
  .site-nav__link {
    display: flex;
    width: 100%;
    padding: var(--space-3) var(--space-2);
    border: 0;
    border-bottom: var(--border-thin) solid var(--color-contrast-line);
    border-radius: 0;
    font-family: var(--font-heading);
    font-size: var(--text-lg);
  }
  .site-nav__link:hover { background-color: transparent; color: var(--color-contrast-accent); }
  .site-nav__link[aria-current="page"] {
    background-color: transparent;
    color: var(--color-contrast-accent);
    border-bottom-color: var(--color-contrast-line);
  }
  .site-nav__link[aria-current="page"] .site-nav__no { color: var(--color-contrast-accent); }
  .site-nav__no { font-size: var(--text-sm); }

  .site-header__actions { margin-inline-start: auto; }
  .site-header__inner { gap: var(--space-2); }
}

@media (max-width: 720px) {
  .grid { gap: var(--space-3); }
  .entry { grid-template-columns: 1fr; }
  .entry__no { margin-bottom: var(--space-1); }
  .idx__head { display: none; }
  .idx__row {
    grid-template-columns: 1fr;
    gap: 4px;
    padding-block: var(--space-2);
    min-height: 0;
  }
  .idx__cell--go { text-align: left; }
  .qa__panel-inner { padding-inline-start: var(--space-3); }
  .footer-col { grid-column: span 6; }
  .footer-col--contact { grid-column: span 12; }
  .footer-wordmark { font-size: calc(var(--text-display) * 1.5); }
  .data-band { padding: var(--space-4) var(--space-3); }
}

@media (max-width: 480px) {
  :root { --gutter: 18px; }
  .footer-col { grid-column: span 12; }
  .footer-tagline { font-size: var(--text-lg); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  [data-reveal] { opacity: 1; transform: none; transition: none; }
  .qa__panel { transition: none; }
  .site-nav { transition: none; }
  .to-top { transition: none; }
  .header-progress { transition: none; }
}