:root {
  --color-surface: #fafafa;
  --color-surface-alt: #f1f1f1;
  --color-surface-deep: #e4e5e5;
  --color-ink: #404947;
  --color-ink-soft: #65716e;
  --color-ink-muted: #7a8583;
  --color-line: #d9dada;
  --color-primary: #5f7c76;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4e8e8;
  --color-accent: #0e866b;
  --color-accent-ink: #ffffff;
  --color-highlight: #d0e5e0;
  --color-focus: #067f64;
  --color-contrast-surface: #1f2322;
  --color-contrast-ink: #e4e7e6;
  --color-contrast-line: #4a4e4d;
  --color-contrast-accent: #18e7b8;
  --overlay-scrim: linear-gradient(180deg, rgba(31, 35, 34, 0.35) 0%, rgba(31, 35, 34, 0.72) 55%, rgba(31, 35, 34, 0.92) 100%);
  --font-heading: STZhongsong, "Source Han Serif SC", "Songti SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 9.3px;
  --text-sm: 13.9px;
  --text-base: 17px;
  --text-lg: 25.5px;
  --text-xl: 38.2px;
  --text-2xl: 57.4px;
  --text-3xl: 86.1px;
  --text-4xl: 129.1px;
  --text-display: clamp(49px, 10.2vw, 130px);
  --text-figure: clamp(41px, 7.3vw, 94px);
  --weight-heading: 390;
  --weight-body: 400;
  --leading-body: 1.77;
  --leading-heading: 1.16;
  --tracking-heading: 0.031em;
  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 0px;
  --radius-pill: 0px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1140px;
  --measure: 58ch;
  --gutter: 16px;
  --section-y: 126px;
  --section-y-lg: 176px;
}

/* ===== reset ===== */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, h5, p, figure, blockquote, dl, dd, ol, ul, pre { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg, video, picture { display: block; max-width: 100%; }
button, input, select, textarea { font: inherit; color: inherit; }
button { background: none; border: 0; padding: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; }
[hidden] { display: none !important; }

/* ===== base ===== */
body {
  background: 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);
  padding-bottom: 44px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  text-wrap: balance;
}
h1 { font-size: var(--text-2xl); }
h2 { font-size: var(--text-xl); }
h3 { font-size: var(--text-lg); }
h4 { font-size: var(--text-base); }
p { text-wrap: pretty; }
::selection { background: var(--color-highlight); color: var(--color-ink); }
:focus-visible { outline: 2px solid var(--color-focus); outline-offset: 3px; }

.shell {
  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); }

.lede {
  font-size: var(--text-lg);
  line-height: 1.5;
  color: var(--color-ink-soft);
  max-width: var(--measure);
}
.prose { max-width: var(--measure); }
.prose > * + * { margin-top: var(--space-3); }
.prose a, .lede a { color: var(--color-accent); text-decoration: underline; text-underline-offset: 4px; text-decoration-thickness: 1px; }
.prose a:hover, .lede a:hover { text-decoration-thickness: 2px; }

.eyebrow {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}
.eyebrow::before {
  content: "";
  width: 22px;
  height: var(--border-thin);
  background: var(--color-primary);
  flex: none;
}
.contrast-panel .eyebrow { color: var(--color-contrast-accent); }
.contrast-panel .eyebrow::before { background: var(--color-contrast-accent); }

.caption,
figcaption {
  font-size: var(--text-sm);
  line-height: 1.55;
  color: var(--color-ink-soft);
  max-width: 52ch;
}
.data, .timecode {
  font-family: var(--font-mono);
  font-size: 0.9em;
  letter-spacing: 0.02em;
  font-variant-numeric: tabular-nums;
}
.timecode { color: var(--color-ink-muted); }

.figure,
.stat-figure {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  line-height: 0.94;
  letter-spacing: -0.02em;
  color: var(--color-ink);
  font-variant-numeric: tabular-nums;
}
.display-hero {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 0.98;
  letter-spacing: var(--tracking-heading);
  text-transform: uppercase;
  color: var(--color-ink);
}

.mark {
  background-image: linear-gradient(transparent 60%, var(--color-highlight) 60%);
  padding-inline: 0.06em;
}
.underline-accent {
  text-decoration: underline;
  text-decoration-color: var(--color-accent);
  text-decoration-thickness: 2px;
  text-underline-offset: 6px;
}

.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  padding-bottom: var(--space-3);
  border-bottom: var(--border-thin) dashed var(--color-line);
  margin-bottom: var(--space-6);
}
.section-head__title { font-size: var(--text-xl); }
.section-head__note {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

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

.cta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
}

/* ===== buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 13px 24px;
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  border: var(--border-thin) solid var(--color-primary);
  transition: background-color .18s ease, color .18s ease, border-color .18s ease;
}
.btn::after { content: "→"; font-family: var(--font-mono); }
.btn:hover { background: var(--color-accent); border-color: var(--color-accent); color: var(--color-accent-ink); }
.btn--ghost { background: transparent; color: var(--color-ink); border-color: var(--color-line); }
.btn--ghost:hover { background: transparent; color: var(--color-accent); border-color: var(--color-accent); }
.btn--dark { background: var(--color-contrast-surface); border-color: var(--color-contrast-surface); color: var(--color-contrast-ink); }
.btn--dark:hover { background: var(--color-accent); border-color: var(--color-accent); color: var(--color-accent-ink); }

/* ===== breadcrumb ===== */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}
.breadcrumb ol { display: flex; flex-wrap: wrap; gap: 6px; }
.breadcrumb li + li::before { content: "/"; margin-right: 6px; color: var(--color-line); }
.breadcrumb a { color: var(--color-ink-soft); }
.breadcrumb a:hover { color: var(--color-accent); }

/* ===== header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: var(--color-surface);
  border-bottom: var(--border-thin) dashed var(--color-line);
}
.skip-link {
  position: absolute;
  left: var(--gutter);
  top: -120px;
  z-index: 90;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding: 10px 18px;
  font-size: var(--text-sm);
  transition: top .18s ease;
}
.skip-link:focus { top: var(--space-1); }

.header-utility { border-bottom: var(--border-thin) dashed var(--color-line); }
.header-utility__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: 9px;
}
.header-brandline {
  font-size: var(--text-xs);
  letter-spacing: 0.13em;
  color: var(--color-ink-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.header-quick {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-soft);
  border-bottom: var(--border-thin) dashed var(--color-line);
  white-space: nowrap;
  flex: none;
}
.header-quick:hover { color: var(--color-accent); border-bottom-color: var(--color-accent); }

.header-main__inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding-block: var(--space-2) 14px;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  flex: none;
  min-width: 0;
}
.brand__mark {
  position: relative;
  width: 12px;
  height: 12px;
  background: var(--color-accent);
  flex: none;
}
.brand__mark::after {
  content: "";
  position: absolute;
  inset: -5px;
  border: var(--border-thin) dashed var(--color-line);
}
.brand__text { display: block; min-width: 0; }
.brand__name {
  display: block;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.05;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
.brand__sub {
  display: block;
  margin-top: 3px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.site-nav { margin-left: auto; }
.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}
.site-nav__list a {
  position: relative;
  display: inline-block;
  padding-block: 6px;
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  white-space: nowrap;
  transition: color .18s ease;
}
.site-nav__list a::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--color-accent);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform .24s ease;
}
.site-nav__list a:hover,
.site-nav__list a:focus-visible { color: var(--color-ink); }
.site-nav__list a:hover::after,
.site-nav__list a:focus-visible::after { transform: scaleX(1); }
.site-nav__list a[aria-current="page"] { color: var(--color-ink); }
.site-nav__list a[aria-current="page"]::after { transform: scaleX(1); }

.header-cta {
  flex: none;
  padding: 10px 18px;
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-surface);
  border-radius: var(--radius-sm);
  transition: background-color .18s ease, color .18s ease, border-color .18s ease;
}
.header-cta:hover {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 9px 12px;
  border: var(--border-thin) solid var(--color-line);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  border-radius: var(--radius-sm);
}
.nav-toggle__bars { display: inline-flex; flex-direction: column; gap: 3px; }
.nav-toggle__bar { display: block; width: 14px; height: var(--border-thin); background: currentColor; }
.nav-toggle[aria-expanded="true"] { border-color: var(--color-accent); color: var(--color-accent); }

/* ===== footer ===== */
.site-footer {
  margin-top: var(--section-y-lg);
  padding-block: var(--space-8) var(--space-6);
  background: var(--color-surface-alt);
  border-top: var(--border-thin) dashed var(--color-line);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.25fr 1fr 0.9fr;
  gap: var(--space-4);
  align-items: start;
}
.footer-panel {
  background: var(--color-surface);
  padding: var(--space-6) var(--space-4) var(--space-4);
  border-top: var(--border-thin) dashed var(--color-line);
}
.footer-panel__title {
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
}
.footer-panel__lede {
  margin-top: var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
}
.footer-panel__note {
  margin-top: var(--space-3);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}
.footer-panel__link {
  display: inline-block;
  margin-top: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-accent);
  border-bottom: var(--border-thin) dashed var(--color-accent);
}
.footer-panel__link:hover { color: var(--color-ink); border-bottom-color: var(--color-ink); }

.footer-facts { margin-top: var(--space-4); display: grid; gap: var(--space-2); }
.footer-facts__row {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr);
  gap: var(--space-2);
  padding-top: var(--space-2);
  border-top: var(--border-thin) dashed var(--color-line);
}
.footer-facts dt {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  padding-top: 2px;
}
.footer-facts__value {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink);
  word-break: break-word;
}

.footer-links { margin-top: var(--space-4); display: grid; gap: 2px; }
.footer-links a {
  display: inline-block;
  padding-block: 5px;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  border-bottom: var(--border-thin) dashed transparent;
  transition: color .18s ease, border-color .18s ease;
}
.footer-links a:hover { color: var(--color-ink); border-bottom-color: var(--color-accent); }

.footer-panel--legal {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top-color: var(--color-contrast-line);
}
.footer-panel--legal .footer-panel__title { color: var(--color-contrast-ink); }
.footer-panel--legal .footer-panel__lede { color: var(--color-contrast-ink); opacity: .78; }
.footer-panel--legal .footer-links { margin-top: var(--space-4); }
.footer-links--legal a { color: var(--color-contrast-ink); }
.footer-links--legal a:hover { color: var(--color-contrast-accent); border-bottom-color: var(--color-contrast-accent); }
.footer-panel--legal :focus-visible { outline-color: var(--color-contrast-accent); }
.footer-legal-line {
  margin-top: var(--space-4);
  padding-top: var(--space-2);
  border-top: var(--border-thin) dashed var(--color-contrast-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-contrast-accent);
}

.footer-base {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-2);
  margin-top: var(--space-8);
  padding-top: var(--space-3);
  border-top: var(--border-thin) dashed var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

/* ===== read progress ===== */
.read-progress {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 70;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) dashed var(--color-contrast-line);
}
.read-progress__inner {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: 9px var(--gutter);
}
.read-progress__label,
.read-progress__value {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  flex: none;
}
.read-progress__label { color: var(--color-contrast-ink); opacity: .62; }
.read-progress__value { color: var(--color-contrast-accent); }
.read-progress__track {
  flex: 1 1 auto;
  height: 3px;
  background: var(--color-contrast-line);
  position: relative;
  overflow: hidden;
}
.read-progress__bar {
  display: block;
  width: 0;
  height: 100%;
  background: var(--color-contrast-accent);
  transition: width .12s linear;
}

/* ===== frame view ===== */
.frame-view {
  position: relative;
  padding: clamp(28px, 5vw, 64px);
  border: var(--border-thin) dashed var(--color-line);
}
.frame-view::before,
.frame-view::after {
  content: "";
  position: absolute;
  width: 16px;
  height: 16px;
  border: 2px solid var(--color-accent);
}
.frame-view::before { top: -2px; left: -2px; border-right: 0; border-bottom: 0; }
.frame-view::after { bottom: -2px; right: -2px; border-left: 0; border-top: 0; }
.frame-view--dark {
  border-color: var(--color-contrast-line);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.frame-view--dark::before,
.frame-view--dark::after { border-color: var(--color-contrast-accent); }

/* ===== contrast panel ===== */
.contrast-panel {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding: clamp(32px, 6vw, 88px);
}
.contrast-panel h1,
.contrast-panel h2,
.contrast-panel h3,
.contrast-panel h4 { color: var(--color-contrast-ink); }
.contrast-panel p { color: var(--color-contrast-ink); }
.contrast-panel a { color: var(--color-contrast-accent); }
.contrast-panel .caption,
.contrast-panel .timecode,
.contrast-panel .data { color: var(--color-contrast-ink); opacity: .72; }
.contrast-panel :focus-visible { outline-color: var(--color-contrast-accent); }
.contrast-panel .stat-figure,
.contrast-panel .figure { color: var(--color-contrast-accent); }

/* ===== axis (horizontal timeline) ===== */
.axis {
  position: relative;
  overflow-x: auto;
  padding-bottom: var(--space-3);
  scrollbar-width: thin;
}
.axis__track {
  position: relative;
  display: flex;
  gap: var(--space-4);
  min-width: max-content;
  padding-top: var(--space-6);
}
.axis__track::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 4px;
  height: var(--border-thin);
  background-image: repeating-linear-gradient(to right, var(--color-line) 0 5px, transparent 5px 13px);
}
.axis__node {
  position: relative;
  flex: none;
  width: 196px;
  padding-top: var(--space-3);
}
.axis__node::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 9px;
  height: 9px;
  background: var(--color-primary);
}
.axis__node--key::before { background: var(--color-accent); }
.axis__time {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}
.axis__title {
  margin-top: var(--space-1);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.25;
  color: var(--color-ink);
}
.axis__note {
  margin-top: var(--space-1);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}
.contrast-panel .axis__track::before {
  background-image: repeating-linear-gradient(to right, var(--color-contrast-line) 0 5px, transparent 5px 13px);
}
.contrast-panel .axis__node::before { background: var(--color-contrast-line); }
.contrast-panel .axis__node--key::before { background: var(--color-contrast-accent); }
.contrast-panel .axis__title { color: var(--color-contrast-ink); }

/* pulse: only runs while in viewport */
[data-pulse]::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 9px;
  height: 9px;
  background: var(--color-accent);
  opacity: 0;
  pointer-events: none;
  animation: kit-pulse 2.4s ease-out infinite;
  animation-play-state: paused;
}
.contrast-panel [data-pulse]::after { background: var(--color-contrast-accent); }
[data-pulse].is-live::after { animation-play-state: running; }
@keyframes kit-pulse {
  0% { transform: scale(1); opacity: .85; }
  70% { transform: scale(2.8); opacity: 0; }
  100% { transform: scale(2.8); opacity: 0; }
}

/* ===== stacked card ===== */
.stack-card {
  position: relative;
  padding-right: 14px;
  padding-bottom: 14px;
}
.stack-card::after {
  content: "";
  position: absolute;
  top: 12px;
  left: 12px;
  right: 0;
  bottom: 0;
  background: var(--color-surface-deep);
}
.stack-card__inner {
  position: relative;
  z-index: 1;
  background: var(--color-surface);
  border: var(--border-thin) dashed var(--color-line);
  padding: var(--space-4);
}

/* ===== index grid ===== */
.index-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(228px, 1fr));
  border-top: var(--border-thin) dashed var(--color-line);
}
.index-grid__item {
  padding: var(--space-4) var(--space-3) var(--space-4) 0;
  border-bottom: var(--border-thin) dashed var(--color-line);
}

/* ===== glossary row ===== */
.glossary-row {
  display: grid;
  grid-template-columns: minmax(150px, 232px) minmax(0, 1fr);
  gap: var(--space-4);
  padding-block: var(--space-4);
  border-bottom: var(--border-thin) dashed var(--color-line);
}
.glossary-row__term {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.25;
  color: var(--color-ink);
}
.glossary-row__body { max-width: var(--measure); }

/* ===== compare ===== */
.compare { border-top: var(--border-thin) solid var(--color-line); }
.compare__row {
  display: grid;
  grid-template-columns: 132px minmax(0, 1fr) minmax(0, 1fr);
  gap: var(--space-3);
  padding: var(--space-3) var(--space-2);
  border-bottom: var(--border-thin) dashed var(--color-line);
}
.compare__row--diff { background: var(--color-highlight); }

/* ===== filter bar ===== */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-3);
  background: var(--color-surface-deep);
  border-top: var(--border-thin) dashed var(--color-line);
  border-bottom: var(--border-thin) dashed var(--color-line);
}
.filter-chip {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  padding: 7px 12px;
  background: transparent;
  border: var(--border-thin) solid var(--color-line);
  color: var(--color-ink-soft);
  border-radius: var(--radius-sm);
  transition: background-color .16s ease, color .16s ease, border-color .16s ease;
}
.filter-chip:hover { border-color: var(--color-primary); color: var(--color-ink); }
.filter-chip[aria-pressed="true"] {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}

/* ===== media ===== */
.media { margin: 0; }
.media__frame {
  position: relative;
  overflow: hidden;
  background: var(--color-surface-deep);
  aspect-ratio: 16 / 9;
}
.media--wide .media__frame { aspect-ratio: 21 / 9; }
.media--portrait .media__frame { aspect-ratio: 3 / 4; }
.media__frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: grayscale(100%) contrast(1.06) brightness(1.02);
}
.media__frame::after {
  content: "";
  position: absolute;
  inset: 0;
  background: color-mix(in srgb, var(--color-primary) 26%, transparent);
  mix-blend-mode: multiply;
  pointer-events: none;
}
.media__overlay {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: flex;
  align-items: flex-end;
  gap: var(--space-2);
  padding: var(--space-4);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
}
.media__overlay .timecode { color: var(--color-contrast-accent); opacity: 1; }
.media__caption {
  margin-top: var(--space-2);
  padding-left: var(--space-2);
  border-left: 2px solid var(--color-line);
  font-size: var(--text-sm);
  line-height: 1.55;
  color: var(--color-ink-soft);
  max-width: 52ch;
}

/* ===== reveal ===== */
.js-reveal [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity .6s ease, transform .6s ease;
  transition-delay: var(--reveal-delay, 0ms);
}
.js-reveal [data-reveal].is-visible { opacity: 1; transform: none; }

/* ===== responsive ===== */
@media (max-width: 1080px) {
  .site-nav__list { gap: var(--space-2); }
}

@media (max-width: 980px) {
  .header-utility__inner { padding-block: 7px; }
  .header-main__inner {
    flex-wrap: wrap;
    row-gap: var(--space-2);
    padding-block: var(--space-2);
  }
  .brand { margin-right: auto; }
  .brand__name { font-size: var(--text-base); }
  .nav-toggle { display: inline-flex; order: 3; }
  .header-cta { order: 2; padding: 9px 14px; font-size: var(--text-xs); letter-spacing: 0.1em; }
  .site-nav {
    order: 4;
    flex-basis: 100%;
    margin-left: 0;
    display: none;
  }
  .site-nav[data-open] { display: block; }
  .site-nav__list {
    gap: var(--space-4);
    padding-top: var(--space-2);
    border-top: var(--border-thin) dashed var(--color-line);
    overflow-x: auto;
    scroll-snap-type: x proximity;
    -webkit-overflow-scrolling: touch;
  }
  .site-nav__list li { flex: none; scroll-snap-align: start; }
  .site-nav__list a { padding-bottom: 8px; }

  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-panel--legal { grid-column: 1 / -1; }
  .compare__row { grid-template-columns: minmax(0, 1fr); }
  .glossary-row { grid-template-columns: minmax(0, 1fr); gap: var(--space-2); }
}

@media (max-width: 720px) {
  body { padding-bottom: 40px; }
  :root { --section-y: 88px; --section-y-lg: 112px; }
  .header-brandline { font-size: var(--text-xs); letter-spacing: 0.06em; }
  .header-quick { display: none; }
  .grid--2, .grid--3 { grid-template-columns: minmax(0, 1fr); }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: var(--space-3); }
  .footer-base { flex-direction: column; gap: 4px; }
  .read-progress__label { display: none; }
  .frame-view { padding: 24px 20px; }
  .index-grid { grid-template-columns: minmax(0, 1fr); }
  .index-grid__item { padding-right: 0; }
  .axis__node { width: 168px; }
}

/* ===== reduced motion ===== */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }
  .js-reveal [data-reveal] { opacity: 1; transform: none; }
  [data-pulse]::after { display: none; }
  .read-progress__bar { transition: none; }
}