:root {
  --color-surface: #fefefe;
  --color-surface-alt: #f5f5f5;
  --color-surface-deep: #e8e8e9;
  --color-ink: #444a50;
  --color-ink-soft: #697078;
  --color-ink-muted: #788087;
  --color-line: #dddedf;
  --color-primary: #4579ab;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4ebf2;
  --color-accent: #0d827b;
  --color-accent-ink: #ffffff;
  --color-highlight: #d3e8e6;
  --color-focus: #057f78;
  --color-contrast-surface: #1d232a;
  --color-contrast-ink: #e4e6e7;
  --color-contrast-line: #494e54;
  --color-contrast-accent: #17e8dc;
  --overlay-scrim: linear-gradient(180deg, rgba(29, 35, 42, 0.35) 0%, rgba(29, 35, 42, 0.72) 55%, rgba(29, 35, 42, 0.92) 100%);
  --font-heading: "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --text-xs: 12.9px;
  --text-sm: 15.5px;
  --text-base: 17px;
  --text-lg: 20.4px;
  --text-xl: 24.5px;
  --text-2xl: 29.4px;
  --text-3xl: 35.3px;
  --text-4xl: 42.3px;
  --text-display: clamp(36px, 7.3vw, 94px);
  --text-figure: clamp(30px, 5.3vw, 68px);
  --weight-heading: 694;
  --weight-body: 400;
  --leading-body: 1.79;
  --leading-heading: 1.16;
  --tracking-heading: -0.002em;
  --radius-sm: 7px;
  --radius-md: 8px;
  --radius-lg: 10px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 6px 18px rgba(68, 74, 80, 0.08);
  --shadow-2: 0 18px 44px rgba(68, 74, 80, 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: 32px;
  --section-y: 81px;
  --section-y-lg: 113px;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 104px;
}

body {
  margin: 0;
  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);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  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-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }

p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }
figure { margin: 0; }
strong { font-weight: var(--weight-heading); }

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

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

: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);
}

/* ---------- containers ---------- */
.container,
.header-frame,
.footer-frame,
.status-grid {
  width: min(100% - var(--space-6), var(--container));
  margin-inline: auto;
}

/* ---------- sections ---------- */
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--alt { background: var(--color-surface-alt); }

.section--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.section--deep h1,
.section--deep h2,
.section--deep h3,
.section--deep h4 { color: var(--color-contrast-ink); }

.section--deep a { color: var(--color-contrast-ink); }

.section--deep ::selection {
  background: color-mix(in srgb, var(--color-contrast-accent) 36%, transparent);
  color: var(--color-contrast-ink);
}

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

.col-4 { grid-column: span 4; }
.col-5 { grid-column: span 5; }
.col-6 { grid-column: span 6; }
.col-7 { grid-column: span 7; }
.col-8 { grid-column: span 8; }
.col-12 { grid-column: span 12; }
.offset-1 { grid-column-start: 2; }

/* ---------- skip link ---------- */
.skip-link {
  position: absolute;
  top: -120px;
  left: var(--space-2);
  z-index: 140;
  padding: 10px var(--space-3);
  border-radius: var(--radius-md);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  transition: top 140ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.skip-link:focus {
  top: var(--space-2);
  text-decoration: none;
}

/* ---------- header ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--color-surface) 88%, transparent);
  backdrop-filter: blur(12px);
  transition: box-shadow 180ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.site-header.is-compact { box-shadow: var(--shadow-1); }

.header-top {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  min-height: 68px;
  transition: min-height 180ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.site-header.is-compact .header-top { min-height: 54px; }

.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  letter-spacing: -0.012em;
  flex: 0 0 auto;
}

.brand:hover { text-decoration: none; }

.brand-glyph {
  align-self: center;
  width: 12px;
  height: 12px;
  border-radius: 3px;
  background: var(--color-primary);
  translate: 0 -1px;
}

.brand-name { font-size: var(--text-lg); }
.brand-suffix {
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
}

.header-tagline {
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-muted);
  white-space: nowrap;
}

.site-nav { margin-left: auto; }

.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-list a {
  display: block;
  padding: 7px 11px;
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  transition: background 120ms cubic-bezier(0.22, 0.61, 0.36, 1),
              color 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.nav-list a:hover {
  background: var(--color-primary-soft);
  color: var(--color-primary);
  text-decoration: none;
}

.nav-list a[aria-current="page"] {
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-weight: var(--weight-heading);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  margin-left: auto;
  padding: 8px 13px;
  border-radius: var(--radius-sm);
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-size: var(--text-sm);
  transition: background 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.nav-toggle:hover { background: var(--color-highlight); }

.nav-toggle-mark {
  display: inline-flex;
  flex-direction: column;
  gap: 4px;
  width: 15px;
}

.nav-toggle-mark i {
  display: block;
  width: 100%;
  height: 1.5px;
  border-radius: 1px;
  background: currentColor;
}

.nav-toggle-mark i:last-child { width: 68%; }

.header-rail {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  padding-bottom: 11px;
}

.quick-lines {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.quick-lines a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 12px 5px 7px;
  border-radius: var(--radius-pill);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  transition: background 120ms cubic-bezier(0.22, 0.61, 0.36, 1),
              color 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.quick-lines a:hover {
  background: var(--color-highlight);
  color: var(--color-accent);
  text-decoration: none;
}

.quick-num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-variant-numeric: tabular-nums;
  color: var(--color-primary);
}

.rail-note {
  margin-left: auto;
  font-size: var(--text-xs);
  font-variant-numeric: tabular-nums;
  color: var(--color-ink-muted);
  white-space: nowrap;
}

.scroll-meter {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  height: 2px;
  background: transparent;
}

.scroll-meter span {
  display: block;
  width: 0;
  height: 100%;
  background: var(--color-accent);
}

/* ---------- footer ---------- */
.site-footer {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding-top: var(--space-8);
  overflow: hidden;
}

.footer-intro { margin-bottom: var(--space-8); }

.footer-kicker {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--color-contrast-accent);
}

.footer-line {
  margin-top: var(--space-2);
  max-width: 30ch;
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: 1.34;
  color: var(--color-contrast-ink);
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: var(--space-6);
}

.footer-col h2 {
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.footer-col ul {
  margin-top: var(--space-2);
  display: grid;
  gap: 10px;
}

.footer-col a {
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 88%, transparent);
}

.footer-col a:hover {
  color: var(--color-contrast-ink);
  text-decoration: underline;
}

.footer-brand {
  margin-top: var(--space-8);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: clamp(52px, 16.4vw, 188px);
  line-height: 0.84;
  letter-spacing: -0.045em;
  color: var(--color-contrast-ink);
  white-space: nowrap;
  overflow: hidden;
}

.footer-meta {
  margin-top: var(--space-6);
  padding-bottom: var(--space-6);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-6);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent);
}

.footer-meta a { color: inherit; }

.footer-meta a:hover { color: var(--color-contrast-ink); }

.status-strip {
  background: color-mix(in srgb, var(--color-contrast-surface) 76%, #000);
  padding-block: 13px;
}

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

.status-cell {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-xs);
  min-width: 0;
}

.status-key {
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent);
  white-space: nowrap;
}

.status-val {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  color: var(--color-contrast-ink);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.status-dot {
  flex: 0 0 auto;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-contrast-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-contrast-accent) 20%, transparent);
}

/* ---------- buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 11px 20px;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.012em;
  text-decoration: none;
  transition: background 140ms cubic-bezier(0.22, 0.61, 0.36, 1),
              color 140ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.btn:hover { text-decoration: none; }

.btn--primary {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

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

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

.btn--ghost:hover {
  background: color-mix(in srgb, var(--color-primary-soft) 62%, var(--color-primary));
  color: var(--color-primary-ink);
}

.btn--onDeep {
  background: var(--color-contrast-ink);
  color: var(--color-contrast-surface);
}

.btn--onDeep:hover {
  background: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
}

/* ---------- breadcrumb ---------- */
.crumb { padding-block: var(--space-3) 0; }

.crumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.crumb li { display: inline-flex; align-items: center; gap: var(--space-1); }

.crumb li + li::before {
  content: "/";
  color: var(--color-ink-muted);
  opacity: 0.5;
}

.crumb a { color: var(--color-ink-muted); }
.crumb a:hover { color: var(--color-primary); }

/* ---------- prose ---------- */
.prose {
  max-width: var(--measure);
  color: var(--color-ink);
}

.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,
.prose ol {
  padding-left: var(--space-3);
  list-style: disc;
}

.prose ol { list-style: decimal; }
.prose li + li { margin-top: 6px; }

.prose a { text-decoration: underline; text-underline-offset: 3px; }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.eyebrow::before {
  content: "";
  width: 18px;
  height: 1.5px;
  background: currentColor;
}

.section--deep .eyebrow { color: var(--color-contrast-accent); }

.meta-line {
  font-size: var(--text-xs);
  font-variant-numeric: tabular-nums;
  color: var(--color-ink-muted);
}

.section--deep .meta-line {
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}

/* ---------- emphasis ---------- */
.quote {
  max-width: var(--measure);
  margin-block: var(--space-6);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  background: var(--color-highlight);
  color: var(--color-ink);
  font-size: var(--text-lg);
  line-height: 1.6;
}

.quote::before {
  content: "\201C";
  display: block;
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  line-height: 0.9;
  color: var(--color-accent);
}

.section--deep .quote {
  background: color-mix(in srgb, var(--color-contrast-accent) 12%, transparent);
  color: var(--color-contrast-ink);
}

/* ---------- figures / numeric ---------- */
.figure {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
  line-height: 1;
}

.figure--xl { font-size: var(--text-figure); }
.figure--lg { font-size: var(--text-4xl); }
.figure--md { font-size: var(--text-2xl); }

.section--deep .figure { color: var(--color-contrast-accent); }

/* ---------- panels ---------- */
.panel-deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-lg);
  padding: var(--space-4);
}

.panel-deep h2,
.panel-deep h3,
.panel-deep h4 { color: var(--color-contrast-ink); }

/* ---------- segmented + filters ---------- */
.segmented {
  display: inline-flex;
  flex-wrap: wrap;
  gap: 4px;
  padding: 4px;
  border-radius: var(--radius-lg);
  background: var(--color-primary-soft);
}

.segmented button {
  padding: 7px 15px;
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-primary);
  transition: background 120ms cubic-bezier(0.22, 0.61, 0.36, 1),
              color 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.segmented button[aria-selected="true"],
.segmented button.is-active {
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-weight: var(--weight-heading);
}

.tag-filter {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.tag-filter button {
  padding: 5px 13px;
  border-radius: var(--radius-pill);
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-size: var(--text-xs);
  transition: background 120ms cubic-bezier(0.22, 0.61, 0.36, 1),
              color 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.tag-filter button:hover { background: var(--color-highlight); }

.tag-filter button[aria-pressed="true"] {
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

/* ---------- index rows ---------- */
.index-row {
  display: grid;
  grid-template-columns: 62px minmax(0, 1fr) auto;
  gap: var(--space-3);
  align-items: baseline;
  padding: 13px 14px;
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
  color: var(--color-ink);
  transition: background 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.index-row:hover {
  background: var(--color-primary-soft);
  text-decoration: none;
}

.index-row .quick-num { color: var(--color-primary); }

/* ---------- anchor rail ---------- */
.anchor-rail {
  position: sticky;
  top: 128px;
  display: grid;
  gap: 10px;
  font-size: var(--text-xs);
  align-content: start;
}

.anchor-rail a {
  position: relative;
  padding-left: 15px;
  color: var(--color-ink-muted);
  transition: color 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.anchor-rail a::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 6px;
  height: 1.5px;
  background: currentColor;
  transform: translateY(-50%);
  transition: width 120ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.anchor-rail a:hover { color: var(--color-primary); text-decoration: none; }

.anchor-rail a.is-active,
.anchor-rail a[aria-current="true"] { color: var(--color-accent); }

.anchor-rail a.is-active::before,
.anchor-rail a[aria-current="true"]::before {
  width: 13px;
  background: var(--color-accent);
}

.section--deep .anchor-rail a { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }
.section--deep .anchor-rail a.is-active { color: var(--color-contrast-accent); }

/* ---------- media ---------- */
.media {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-lg);
  background: var(--color-contrast-surface);
  aspect-ratio: 16 / 10;
  isolation: isolate;
}

.media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
  pointer-events: none;
  z-index: 1;
}

.media--wide { aspect-ratio: 21 / 9; }
.media--tall { aspect-ratio: 4 / 5; }
.media--square { aspect-ratio: 1 / 1; }

.media-caption {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  z-index: 2;
  padding: var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
}

/* ---------- reveal ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 220ms cubic-bezier(0.22, 0.61, 0.36, 1),
              transform 220ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

[data-reveal="shown"] {
  opacity: 1;
  transform: none;
}

html:not(.js) [data-reveal] {
  opacity: 1;
  transform: none;
}

/* ---------- responsive ---------- */
@media (max-width: 1024px) {
  .grid { grid-template-columns: repeat(6, 1fr); }
  .col-4,
  .col-5,
  .col-6 { grid-column: span 3; }
  .col-7,
  .col-8,
  .col-12 { grid-column: span 6; }
  .offset-1 { grid-column-start: auto; }
  .header-tagline { display: none; }
}

@media (max-width: 900px) {
  html { scroll-padding-top: 84px; }

  .header-top {
    flex-wrap: wrap;
    row-gap: var(--space-2);
    padding-bottom: 0;
  }

  .site-header[data-open] .header-top { padding-bottom: var(--space-2); }

  .nav-toggle { display: inline-flex; }

  .site-nav {
    display: none;
    flex: 0 0 100%;
    order: 3;
    margin-left: 0;
  }

  .site-header[data-open] .site-nav { display: block; }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .nav-list a { padding: 12px 14px; font-size: var(--text-base); }

  .header-rail { display: none; }

  .site-header[data-open] .header-rail {
    display: block;
    padding-bottom: var(--space-3);
  }

  .quick-lines { gap: 6px; }
  .rail-note { margin-left: 0; margin-top: var(--space-2); }

  .anchor-rail { position: static; }
}

@media (max-width: 720px) {
  .grid { grid-template-columns: 1fr; gap: var(--space-4); }
  .grid > * { grid-column: auto; }
  .section { padding-block: var(--space-6); }
  .section--lg { padding-block: var(--space-8); }
  .status-grid { grid-template-columns: repeat(2, 1fr); }
  .status-cell:nth-child(3) { display: none; }
  .index-row { grid-template-columns: 44px minmax(0, 1fr); }
  .index-row > :last-child { grid-column: 2; }
  .footer-meta { gap: var(--space-1) var(--space-3); }
}

/* ---------- motion preferences ---------- */
@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;
  }

  [data-reveal] {
    opacity: 1;
    transform: none;
  }
}