:root {
  --color-surface: #f9f9f9;
  --color-surface-alt: #f1f0f1;
  --color-surface-deep: #e5e4e5;
  --color-ink: #504653;
  --color-ink-soft: #786a7b;
  --color-ink-muted: #847788;
  --color-line: #dbd9db;
  --color-primary: #a243bc;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #ede0f0;
  --color-accent: #5227d8;
  --color-accent-ink: #ffffff;
  --color-highlight: #dbd3f3;
  --color-focus: #4c1be4;
  --color-contrast-surface: #1a121c;
  --color-contrast-ink: #e6e4e7;
  --color-contrast-line: #474049;
  --color-contrast-accent: #8a6ce4;
  --overlay-scrim: linear-gradient(180deg, rgba(26, 18, 28, 0.35) 0%, rgba(26, 18, 28, 0.72) 55%, rgba(26, 18, 28, 0.92) 100%);
  --font-heading: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-body: "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 12.2px;
  --text-sm: 15.2px;
  --text-base: 17px;
  --text-lg: 21.2px;
  --text-xl: 26.6px;
  --text-2xl: 33.2px;
  --text-3xl: 41.5px;
  --text-4xl: 51.9px;
  --text-display: clamp(39px, 8.0vw, 102px);
  --text-figure: clamp(32px, 5.7vw, 73px);
  --weight-heading: 766;
  --weight-body: 400;
  --leading-body: 1.75;
  --leading-heading: 1.26;
  --tracking-heading: 0.009em;
  --radius-sm: 14px;
  --radius-md: 16px;
  --radius-lg: 18px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 6px 18px rgba(80, 70, 83, 0.08);
  --shadow-2: 0 18px 44px rgba(80, 70, 83, 0.14);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1180px;
  --measure: 72ch;
  --gutter: 24px;
  --section-y: 85px;
  --section-y-lg: 119px;
}

/* ================= reset ================= */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; text-size-adjust: 100%; scroll-behavior: smooth; }
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;
  text-rendering: optimizeLegibility;
}
h1, h2, h3, h4, h5, h6 {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }
h5, h6 { font-size: var(--text-base); }
p { margin: 0 0 var(--space-3); }
p:last-child { margin-bottom: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
img, svg, video, canvas { display: block; max-width: 100%; }
a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; text-underline-offset: 0.22em; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
table { border-collapse: collapse; width: 100%; }
::selection { background: var(--color-highlight); color: var(--color-ink); }
:focus-visible { outline: 3px solid var(--color-focus); outline-offset: 2px; border-radius: 6px; }
[hidden] { display: none !important; }

/* ================= type utilities ================= */
.type-display {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-display);
  line-height: 1;
  letter-spacing: -0.012em;
}
.type-figure {
  font-family: var(--font-mono);
  font-weight: var(--weight-heading);
  font-size: var(--text-figure);
  line-height: 0.94;
  letter-spacing: 0.02em;
}
.mono { font-family: var(--font-mono); letter-spacing: 0.06em; }
.meta {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}
.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background-color: currentColor;
}
.link { font-weight: 600; color: var(--color-accent); }
.visually-hidden {
  position: absolute; width: 1px; height: 1px; margin: -1px;
  padding: 0; overflow: hidden; clip: rect(0 0 0 0); clip-path: inset(50%); white-space: nowrap;
}

/* ================= layout ================= */
.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-8); }
.section--alt { background-color: var(--color-surface-alt); }
.section--deep { background-color: var(--color-surface-deep); }
.section--contrast {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--contrast h1,
.section--contrast h2,
.section--contrast h3,
.section--contrast h4 { color: var(--color-contrast-ink); }
.section--contrast a { color: var(--color-contrast-accent); }
.section--contrast .section-lede,
.section--contrast .lede { color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent); }
.section--contrast .section-head__num { color: var(--color-contrast-accent); }
.section--contrast .eyebrow { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }
.section--contrast .frame {
  border-color: var(--color-contrast-line);
  background-color: color-mix(in srgb, var(--color-contrast-ink) 6%, transparent);
}

.measure { max-width: var(--measure); }

.grid { display: grid; gap: var(--space-3); }
.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid--split { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); }
.grid--gap-lg { gap: var(--space-4); }

.prose { max-width: var(--measure); }
.prose > * + * { margin-top: var(--space-3); }
.prose h2 { margin-top: var(--space-6); font-size: var(--text-2xl); }
.prose h3 { margin-top: var(--space-4); font-size: var(--text-xl); }
.prose ul { display: grid; gap: var(--space-1); }
.prose ul li { position: relative; padding-left: var(--space-3); }
.prose ul li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.74em;
  width: 6px;
  height: 6px;
  border-radius: 2px;
  background-color: var(--color-primary);
  transform: rotate(45deg);
}

/* ================= frames, blocks, ornaments ================= */
.frame {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  padding: var(--space-4);
}
.frame--inset {
  background-color: var(--color-surface-deep);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--color-line) 72%, transparent);
}
.block {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  padding: var(--space-4);
}
.block--raised { box-shadow: var(--shadow-2); }
.block--quiet { background-color: transparent; border-radius: var(--radius-md); }
.block--tint {
  background-image: linear-gradient(158deg, var(--color-primary-soft) 0%, var(--color-surface) 68%);
  border-color: color-mix(in srgb, var(--color-primary) 26%, var(--color-line));
}
.block--contrast {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-color: var(--color-contrast-line);
}
.block--contrast h1, .block--contrast h2, .block--contrast h3 { color: var(--color-contrast-ink); }
.block--contrast a { color: var(--color-contrast-accent); }

.section-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-4);
  align-items: start;
  margin-bottom: var(--space-6);
}
.section-head__num {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 0.86;
  letter-spacing: 0.02em;
  color: color-mix(in srgb, var(--color-primary) 82%, var(--color-ink-muted));
}
.section-head__body { max-width: var(--measure); }
.section-title { font-size: var(--text-3xl); }
.section-lede,
.lede {
  margin-top: var(--space-2);
  font-size: var(--text-lg);
  line-height: 1.55;
  color: var(--color-ink-soft);
}
.chapter-num {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 0.9;
  letter-spacing: 0.02em;
  color: color-mix(in srgb, var(--color-primary) 74%, var(--color-ink-muted));
}
.slash {
  height: 6px;
  border: 0;
  margin: var(--space-3) 0;
  background-image: linear-gradient(90deg, var(--color-accent), var(--color-primary) 55%, var(--color-primary-soft));
  clip-path: polygon(0 0, 100% 0, 94% 100%, 0 100%);
}

/* ================= buttons, tags ================= */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  min-height: 48px;
  padding: 0 var(--space-4);
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-pill);
  font-size: var(--text-base);
  font-weight: 600;
  line-height: 1.2;
  text-decoration: none;
  transition: transform 0.18s ease, background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease, box-shadow 0.18s ease;
}
.btn:hover { text-decoration: none; transform: translateY(-2px); }
.btn--small { min-height: 40px; padding: 0 var(--space-3); font-size: var(--text-sm); }
.btn--primary {
  background-image: linear-gradient(135deg, var(--color-accent), var(--color-primary));
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-1);
}
.btn--ghost {
  border-color: color-mix(in srgb, var(--color-primary) 40%, var(--color-line));
  background-color: color-mix(in srgb, var(--color-primary-soft) 55%, transparent);
  color: var(--color-accent);
}
.btn--quiet {
  border-color: var(--color-line);
  background-color: transparent;
  color: var(--color-accent);
}
.btn--contrast {
  background-color: var(--color-contrast-ink);
  color: var(--color-contrast-surface);
}
.section--contrast .btn--ghost,
.block--contrast .btn--ghost {
  border-color: color-mix(in srgb, var(--color-contrast-accent) 55%, transparent);
  background-color: color-mix(in srgb, var(--color-contrast-accent) 16%, transparent);
  color: var(--color-contrast-ink);
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 30%, var(--color-line));
  border-radius: var(--radius-pill);
  background-color: color-mix(in srgb, var(--color-primary-soft) 70%, transparent);
  color: var(--color-accent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}

/* ================= rows & timeline ================= */
.rows {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}
.rows > * + * { border-top: var(--border-thin) solid var(--color-line); }
.row {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: var(--space-2);
  align-items: baseline;
  padding: var(--space-3);
  color: inherit;
  text-decoration: none;
  transition: background-color 0.18s ease, box-shadow 0.18s ease;
}
.row:hover {
  background-color: var(--color-surface-alt);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--color-primary) 46%, var(--color-line));
  text-decoration: none;
}
.row__num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
  transition: color 0.18s ease;
}
.row:hover .row__num { color: var(--color-accent); }
.row__title { font-family: var(--font-heading); font-size: var(--text-lg); font-weight: var(--weight-heading); }

.timeline { display: grid; }
.timeline__item {
  position: relative;
  padding: var(--space-4) 0 var(--space-4) var(--space-6);
  border-top: var(--border-thin) solid var(--color-line);
}
.timeline__item:first-child { border-top: 0; }
.timeline__item::before {
  content: "";
  position: absolute;
  left: 5px;
  top: calc(var(--space-4) + 0.55em);
  width: 8px;
  height: 8px;
  border-radius: 3px;
  background-color: var(--color-primary);
  transform: rotate(45deg);
}
.timeline__item::after {
  content: "";
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 1px;
  background-color: var(--color-line);
}
.timeline__item:last-child::after { bottom: auto; height: calc(var(--space-4) + 0.55em); }

/* ================= media containers ================= */
.media {
  position: relative;
  aspect-ratio: 16 / 9;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  background-image: linear-gradient(150deg, var(--color-primary-soft) 0%, var(--color-surface-deep) 62%, var(--color-surface-alt) 100%);
  overflow: hidden;
}
.media--tall { aspect-ratio: 4 / 5; }
.media--square { aspect-ratio: 1 / 1; }
.media > img,
.media > svg { width: 100%; height: 100%; object-fit: cover; }
.media__placeholder {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.16em;
  color: color-mix(in srgb, var(--color-primary) 52%, var(--color-ink-muted));
}
.media__scrim {
  position: absolute;
  inset: 0;
  background-image: var(--overlay-scrim);
}
.media__caption {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  margin: 0;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
}

/* ================= breadcrumbs & skip link ================= */
.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}
.breadcrumbs__item + .breadcrumbs__item::before {
  content: "／";
  margin-right: var(--space-1);
  color: color-mix(in srgb, var(--color-ink-muted) 62%, transparent);
}
.breadcrumbs a { color: var(--color-ink-soft); }
.breadcrumbs [aria-current="page"] { color: var(--color-accent); }

.skip-link {
  position: absolute;
  left: var(--gutter);
  top: -72px;
  z-index: 140;
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 var(--space-3);
  border-radius: 0 0 var(--radius-md) var(--radius-md);
  background-color: var(--color-accent);
  color: var(--color-accent-ink);
  font-size: var(--text-sm);
  transition: top 0.2s ease;
}
.skip-link:focus { top: 0; text-decoration: none; }

/* ================= header ================= */
.site-header { position: sticky; top: 0; z-index: 70; }
.site-header__frame {
  position: relative;
  max-width: var(--container);
  margin-inline: auto;
  padding: 0 var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-top: 0;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  background-image: linear-gradient(180deg, var(--color-surface) 0%, color-mix(in srgb, var(--color-primary-soft) 42%, var(--color-surface)) 100%);
  box-shadow: var(--shadow-1);
  transition: border-color 0.25s ease, box-shadow 0.25s ease;
}
.site-header[data-scrolled="true"] .site-header__frame {
  border-color: color-mix(in srgb, var(--color-primary) 34%, var(--color-line));
  box-shadow: var(--shadow-2);
}
.site-header__bar {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  min-height: 78px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  flex: 0 0 auto;
  color: var(--color-ink);
  text-decoration: none;
}
.brand:hover { text-decoration: none; }
.brand__mark {
  width: 34px;
  height: 34px;
  color: var(--color-ink);
  transition: color 0.22s ease, transform 0.3s ease;
}
.brand:hover .brand__mark,
.brand:focus-visible .brand__mark { color: var(--color-accent); transform: translateY(-1px); }
.brand__text { display: flex; flex-direction: column; line-height: 1.15; }
.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: 0.06em;
}
.brand__sub {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.nav { margin-left: auto; }
.nav__list { display: flex; align-items: stretch; }
.nav__item + .nav__item { border-left: var(--border-thin) solid var(--color-line); }
.nav__link {
  display: inline-flex;
  align-items: center;
  height: 78px;
  padding: 0 var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  text-decoration: none;
  transition: color 0.18s ease, background-color 0.18s ease;
}
.nav__link:hover {
  color: var(--color-accent);
  background-color: color-mix(in srgb, var(--color-primary-soft) 62%, transparent);
  text-decoration: none;
}
.nav__link[aria-current="page"] {
  color: var(--color-accent);
  background-color: var(--color-highlight);
  font-weight: 600;
}
.nav__aside { display: none; }

.header-utility {
  display: flex;
  align-items: center;
  padding-left: var(--space-3);
  border-left: var(--border-thin) solid var(--color-line);
}
.utility-link {
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  white-space: nowrap;
}
.utility-link:hover { color: var(--color-accent); }

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  margin-left: auto;
  min-height: 44px;
  padding: 0 var(--space-3);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 32%, var(--color-line));
  border-radius: var(--radius-pill);
  background-color: color-mix(in srgb, var(--color-surface) 74%, transparent);
  color: var(--color-ink);
  font-size: var(--text-sm);
}
.nav-toggle__bars { position: relative; display: block; width: 18px; height: 12px; }
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  border-radius: 2px;
  background-color: currentColor;
  transition: transform 0.26s ease, top 0.26s ease, bottom 0.26s ease;
}
.nav-toggle__bars::before { top: 0; }
.nav-toggle__bars::after { bottom: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before { top: 5px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { bottom: 5px; transform: rotate(-45deg); }

.scroll-progress {
  position: absolute;
  left: var(--radius-lg);
  right: var(--radius-lg);
  bottom: 0;
  height: 2px;
  overflow: hidden;
  border-radius: var(--radius-pill);
  background-color: color-mix(in srgb, var(--color-line) 70%, transparent);
}
.scroll-progress__bar {
  display: block;
  width: 0;
  height: 100%;
  background-image: linear-gradient(90deg, var(--color-accent), var(--color-primary));
  transition: width 0.12s linear;
}

.nav-scrim {
  position: fixed;
  inset: 0;
  z-index: 75;
  background-image: var(--overlay-scrim);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}
.nav-scrim[data-open="true"] { opacity: 1; pointer-events: auto; }

/* ================= side rail ================= */
.rail {
  position: fixed;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  z-index: 60;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 2px;
  padding: var(--space-2) var(--space-1) var(--space-2) var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-right: 0;
  border-radius: var(--radius-lg) 0 0 var(--radius-lg);
  background-color: color-mix(in srgb, var(--color-surface) 82%, transparent);
  box-shadow: var(--shadow-1);
}
.rail__list { display: grid; gap: 2px; }
.rail__link,
.rail__to-top {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  min-height: 34px;
  padding: 0 var(--space-2);
  border-radius: var(--radius-pill);
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  text-decoration: none;
  transition: color 0.18s ease, background-color 0.18s ease;
}
.rail__link:hover,
.rail__to-top:hover { color: var(--color-accent); text-decoration: none; }
.rail__link[aria-current="page"] { color: var(--color-accent); background-color: var(--color-highlight); }
.rail__dot {
  flex: 0 0 auto;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: currentColor;
}
.rail__dot--arrow {
  width: 7px;
  height: 7px;
  border-radius: 0;
  border-top: 1.5px solid currentColor;
  border-left: 1.5px solid currentColor;
  background-color: transparent;
  transform: rotate(45deg);
}
.rail__to-top { margin-top: var(--space-1); border-top: var(--border-thin) solid var(--color-line); border-radius: 0 0 var(--radius-pill) var(--radius-pill); }
.rail__label {
  max-width: 0;
  overflow: hidden;
  white-space: nowrap;
  opacity: 0;
  transition: max-width 0.28s ease, opacity 0.2s ease;
}
.rail:hover .rail__label,
.rail:focus-within .rail__label { max-width: 8em; opacity: 1; }

/* ================= footer ================= */
.site-footer {
  margin-top: var(--section-y);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  background-image:
    radial-gradient(120% 82% at 10% 0%, color-mix(in srgb, var(--color-primary) 26%, transparent) 0%, transparent 58%),
    radial-gradient(90% 70% at 92% 8%, color-mix(in srgb, var(--color-accent) 22%, transparent) 0%, transparent 62%);
}
.site-footer__inner { padding-block: var(--section-y) var(--space-6); }
.site-footer h1, .site-footer h2, .site-footer h3 { color: var(--color-contrast-ink); }
.site-footer a { color: var(--color-contrast-ink); }

.footer-top {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.3fr;
  gap: var(--space-4);
  padding-bottom: var(--space-6);
}
.footer-col {
  padding-left: var(--space-4);
  border-left: var(--border-thin) solid var(--color-contrast-line);
}
.footer-col--brand { padding-left: 0; border-left: 0; }
.footer-brand { display: flex; align-items: center; gap: var(--space-2); margin-bottom: var(--space-2); }
.footer-brand .brand__mark { width: 32px; height: 32px; color: var(--color-contrast-accent); }
.footer-brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: 0.06em;
  color: var(--color-contrast-ink);
}
.footer-title {
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.16em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}
.footer-list { display: grid; gap: 2px; }
.footer-link {
  display: inline-block;
  padding: 4px 0;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  text-decoration: none;
}
.footer-link:hover { color: var(--color-contrast-accent); text-decoration: underline; text-underline-offset: 0.22em; }
.footer-note {
  margin-top: var(--space-2);
  max-width: 46ch;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
}
.footer-legal {
  margin-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-contrast-accent);
}
.contact-list { display: grid; gap: var(--space-1); }
.contact-list li { display: flex; gap: var(--space-2); align-items: baseline; font-size: var(--text-sm); }
.contact-list__k {
  flex: 0 0 auto;
  min-width: 3.2em;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}
.contact-list__v { color: var(--color-contrast-ink); }

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}
.footer-hint {
  flex: 1 1 420px;
  margin: 0;
  padding: var(--space-2) var(--space-3);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
}
.footer-copy {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent);
}

/* ================= motion ================= */
html[data-motion="on"] [data-reveal] {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.6s ease, transform 0.6s cubic-bezier(0.22, 0.7, 0.28, 1);
  transition-delay: var(--reveal-delay, 0ms);
  will-change: opacity, transform;
}
html[data-motion="on"] [data-reveal][data-revealed="true"] {
  opacity: 1;
  transform: none;
}

/* ================= responsive ================= */
@media (max-width: 1240px) {
  .rail { display: none; }
}

@media (max-width: 1000px) {
  .header-utility { display: none; }
  .nav-toggle { display: inline-flex; }
  .nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    width: min(330px, 84vw);
    margin: 0;
    padding: calc(var(--space-8) + var(--space-2)) var(--space-4) var(--space-4);
    overflow-y: auto;
    background-color: color-mix(in srgb, var(--color-contrast-surface) 92%, transparent);
    -webkit-backdrop-filter: blur(18px);
    backdrop-filter: blur(18px);
    border-left: var(--border-thin) solid var(--color-contrast-line);
    color: var(--color-contrast-ink);
    transform: translateX(102%);
    transition: transform 0.34s cubic-bezier(0.22, 0.7, 0.28, 1);
    z-index: 80;
  }
  .nav[data-open="true"] { transform: translateX(0); }
  .nav__list { flex-direction: column; align-items: stretch; }
  .nav__item + .nav__item {
    border-left: 0;
    border-top: var(--border-thin) solid var(--color-contrast-line);
  }
  .nav__link {
    height: auto;
    padding: var(--space-3) var(--space-1);
    font-size: var(--text-lg);
    color: var(--color-contrast-ink);
  }
  .nav__link:hover {
    background-color: color-mix(in srgb, var(--color-contrast-accent) 16%, transparent);
    color: var(--color-contrast-accent);
  }
  .nav__link[aria-current="page"] {
    background-color: color-mix(in srgb, var(--color-contrast-accent) 26%, transparent);
    color: var(--color-contrast-accent);
  }
  .nav__aside {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: var(--space-2);
    margin-top: var(--space-4);
    padding-top: var(--space-3);
    border-top: var(--border-thin) solid var(--color-contrast-line);
  }
  .nav__aside .utility-link { color: var(--color-contrast-ink); }
  .nav__aside .btn--quiet {
    border-color: var(--color-contrast-line);
    color: var(--color-contrast-ink);
  }
  .nav [class*="__link"]:focus-visible,
  .nav button:focus-visible { outline-color: var(--color-contrast-accent); }

  .grid--3, .grid--4, .grid--split { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-top { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-col {
    padding-left: 0;
    border-left: 0;
    padding-top: var(--space-4);
    border-top: var(--border-thin) solid var(--color-contrast-line);
  }
  .footer-col:first-child { padding-top: 0; border-top: 0; }
}

@media (max-width: 760px) {
  .section-head { grid-template-columns: minmax(0, 1fr); gap: var(--space-2); }
  .footer-bottom { align-items: flex-start; }
}

@media (max-width: 640px) {
  :root { --gutter: 16px; }
  .site-header__bar { min-height: 68px; }
  .nav__link { height: 68px; }
  .brand__name { font-size: var(--text-lg); }
  .section { padding-block: var(--space-8); }
  .section--lg { padding-block: var(--section-y); }
  .grid--2, .grid--3, .grid--4, .grid--split { grid-template-columns: minmax(0, 1fr); }
  .footer-top { grid-template-columns: minmax(0, 1fr); }
  .row { grid-template-columns: auto minmax(0, 1fr); }
  .row__aside { grid-column: 2; }
  .scroll-progress { left: var(--space-2); right: var(--space-2); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
  html[data-motion="on"] [data-reveal] { opacity: 1; transform: none; }
  .nav { transition: none; }
}