:root {
  --color-surface: #fcfcfc;
  --color-surface-alt: #f4f3f3;
  --color-surface-deep: #e8e6e6;
  --color-ink: #524747;
  --color-ink-soft: #7a6b6b;
  --color-ink-muted: #867979;
  --color-line: #dddbdb;
  --color-primary: #8d6d6d;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #ece8e8;
  --color-accent: #e11f1e;
  --color-accent-ink: #ffffff;
  --color-highlight: #f7d4d4;
  --color-focus: #e41111;
  --color-contrast-surface: #262222;
  --color-contrast-ink: #e7e4e4;
  --color-contrast-line: #504d4d;
  --color-contrast-accent: #e95959;
  --overlay-scrim: linear-gradient(180deg, rgba(38, 34, 34, 0.35) 0%, rgba(38, 34, 34, 0.72) 55%, rgba(38, 34, 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: 10.1px;
  --text-sm: 14.3px;
  --text-base: 17px;
  --text-lg: 24.0px;
  --text-xl: 34.0px;
  --text-2xl: 48.1px;
  --text-3xl: 68.0px;
  --text-4xl: 96.1px;
  --text-display: clamp(42px, 8.7vw, 111px);
  --text-figure: clamp(35px, 6.2vw, 80px);
  --weight-heading: 388;
  --weight-body: 400;
  --leading-body: 1.84;
  --leading-heading: 1.25;
  --tracking-heading: 0.004em;
  --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: 1200px;
  --measure: 63ch;
  --gutter: 32px;
  --section-y: 113px;
  --section-y-lg: 158px;
}

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

html {
  -webkit-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);
}

p { margin: 0; }
figure { margin: 0; }

ul, ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

a {
  color: inherit;
  text-decoration: none;
}

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

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

dl, dd { margin: 0; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
}

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

/* ---------- skip link ---------- */
.skip-link {
  position: fixed;
  top: -120px;
  left: var(--space-3);
  z-index: 400;
  display: inline-block;
  padding: var(--space-2) var(--space-3);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  transition: top 0.18s ease-out;
}

.skip-link:focus {
  top: var(--space-3);
}

/* ---------- layout ---------- */
.container {
  width: min(var(--container), 100% - var(--space-6));
  margin-inline: auto;
}

.section {
  padding-block: var(--section-y);
}

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

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

@media (min-width: 901px) {
  .lg-3 { grid-column: span 3; }
  .lg-4 { grid-column: span 4; }
  .lg-5 { grid-column: span 5; }
  .lg-7 { grid-column: span 7; }
  .lg-8 { grid-column: span 8; }
  .lg-9 { grid-column: span 9; }
  .lg-12 { grid-column: span 12; }
}

.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.prose p + p { margin-top: var(--space-3); }

.prose h2 {
  margin-top: var(--space-8);
  font-size: var(--text-xl);
}

.prose h3 {
  margin-top: var(--space-6);
  font-size: var(--text-lg);
}

.prose ul, .prose ol {
  margin-top: var(--space-3);
  display: grid;
  gap: var(--space-2);
}

.prose li {
  position: relative;
  padding-left: var(--space-4);
}

.prose li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.9em;
  width: 14px;
  height: 1px;
  background-color: var(--color-primary);
}

.lede {
  max-width: var(--measure);
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink-soft);
}

/* ---------- emphasis ---------- */
.mark {
  background-image: linear-gradient(var(--color-accent), var(--color-accent));
  background-repeat: no-repeat;
  background-size: 100% 2px;
  background-position: 0 100%;
  padding-bottom: 2px;
}

.hl {
  background-color: var(--color-highlight);
  padding: 0 0.22em;
}

/* ---------- section head ---------- */
.section-head {
  display: grid;
  gap: var(--space-3);
  margin-bottom: var(--space-6);
}

.section-num {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 0.9;
  letter-spacing: -0.03em;
  color: var(--color-primary);
}

.section-title {
  font-size: var(--text-2xl);
  max-width: 22ch;
}

.section-lede {
  max-width: var(--measure);
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink-soft);
}

/* ---------- placard / caption ---------- */
.placard {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  align-items: baseline;
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.placard__num {
  font-family: var(--font-mono);
  color: var(--color-primary);
  letter-spacing: 0.02em;
}

/* ---------- header ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 120;
  background-color: transparent;
  border-bottom: var(--border-thin) solid transparent;
  transition: background-color 0.2s ease-out, border-color 0.2s ease-out;
}

.site-header[data-pinned="true"] {
  background-color: var(--color-surface);
  border-bottom-color: var(--color-line);
}

.site-header__inner {
  width: min(var(--container), 100% - var(--space-6));
  margin-inline: auto;
  min-height: 78px;
  padding-block: var(--space-2);
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 2px;
  flex: 0 0 auto;
}

.brand__mark {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--color-ink);
}

.brand__line {
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.site-nav {
  margin-inline-start: auto;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-6);
}

.site-nav__link {
  position: relative;
  display: inline-block;
  padding-block: var(--space-1);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  color: var(--color-ink-soft);
  transition: color 0.18s ease-out;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background-color: var(--color-primary);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.2s ease-out;
}

.site-nav__link:hover { color: var(--color-ink); }
.site-nav__link:hover::after { transform: scaleX(1); }

.site-nav__link[aria-current="page"] {
  color: var(--color-ink);
}

.site-nav__link[aria-current="page"]::after {
  transform: scaleX(1);
}

.site-nav__utility {
  display: none;
}

.site-header__meta {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex: 0 0 auto;
}

.round-chip {
  display: inline-flex;
  align-items: baseline;
  gap: var(--space-1);
  padding-left: var(--space-3);
  border-left: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.round-chip__val {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  color: var(--color-primary);
}

.nav-toggle {
  display: none;
  align-items: center;
  padding: var(--space-1) var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink);
  transition: background-color 0.18s ease-out, border-color 0.18s ease-out;
}

.nav-toggle:hover {
  background-color: var(--color-primary-soft);
  border-color: var(--color-primary);
}

.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -1px;
  height: 2px;
  background-color: var(--color-accent);
  transform: scaleX(var(--progress, 0));
  transform-origin: left center;
  opacity: 0;
  transition: opacity 0.18s ease-out;
}

.site-header[data-pinned="true"] .scroll-progress {
  opacity: 1;
}

html[data-nav-open="true"] body {
  overflow: hidden;
}

/* ---------- footer ---------- */
.site-footer {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  padding-block: var(--space-8) var(--space-6);
}

.site-footer__inner {
  width: min(var(--container), 100% - var(--space-6));
  margin-inline: auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}

.site-footer__mark {
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  font-weight: var(--weight-heading);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--color-contrast-ink);
}

.site-footer__statement {
  max-width: var(--measure);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1.5;
  color: var(--color-contrast-ink);
}

.site-footer__contact {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-3);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.site-footer__cell dt {
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-contrast-accent);
  margin-bottom: var(--space-1);
}

.site-footer__cell dd {
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-contrast-ink);
}

.site-footer__contact .is-num {
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

.site-footer__legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3) var(--space-4);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-contrast-ink);
}

.region-badge {
  font-family: var(--font-mono);
  letter-spacing: 0.14em;
  padding: 3px var(--space-1);
  border: var(--border-thin) solid var(--color-contrast-line);
  color: var(--color-contrast-ink);
}

.site-footer__links ul {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.site-footer__links a {
  padding-bottom: 2px;
  border-bottom: 1px solid var(--color-contrast-accent);
  color: var(--color-contrast-ink);
  transition: color 0.18s ease-out, border-color 0.18s ease-out;
}

.site-footer__links a:hover,
.site-footer__links a:focus-visible {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.site-footer__icp,
.site-footer__copy {
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

/* ---------- buttons & links ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-4);
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  transition: background-color 0.18s ease-out, color 0.18s ease-out;
}

.btn:hover,
.btn:focus-visible {
  background-color: var(--color-accent);
  color: var(--color-accent-ink);
}

.btn--ghost {
  background-color: transparent;
  color: var(--color-ink);
  outline: var(--border-thin) solid var(--color-line);
  outline-offset: -1px;
  transition: background-color 0.18s ease-out, color 0.18s ease-out, outline-color 0.18s ease-out;
}

.btn--ghost:hover,
.btn--ghost:focus-visible {
  background-color: var(--color-primary-soft);
  color: var(--color-ink);
  outline-color: var(--color-primary);
}

.link-more {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding-bottom: 3px;
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  border-bottom: 2px solid var(--color-accent);
  transition: border-color 0.18s ease-out, color 0.18s ease-out;
}

.link-more::after {
  content: "→";
  font-family: var(--font-mono);
  transition: transform 0.18s ease-out;
}

.link-more:hover,
.link-more:focus-visible {
  border-bottom-color: var(--color-primary);
  color: var(--color-primary);
}

.link-more:hover::after {
  transform: translateX(4px);
}

/* ---------- breadcrumb ---------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  padding-block: var(--space-6) 0;
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.breadcrumb li + li::before {
  content: "/";
  margin-right: var(--space-2);
  color: var(--color-line);
}

.breadcrumb a {
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  transition: border-color 0.18s ease-out, color 0.18s ease-out;
}

.breadcrumb a:hover,
.breadcrumb a:focus-visible {
  color: var(--color-ink);
  border-bottom-color: var(--color-primary);
}

/* ---------- figures ---------- */
.figure {
  position: relative;
  display: block;
  overflow: hidden;
  background-color: var(--color-surface-deep);
}

.figure__media {
  display: block;
  width: 100%;
  height: 100%;
}

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

.figure--wide { aspect-ratio: 21 / 9; }
.figure--tall { aspect-ratio: 3 / 4; }
.figure--square { aspect-ratio: 1 / 1; }
.figure--panorama { aspect-ratio: 32 / 11; }

.figure__scrim {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: var(--space-6) var(--space-4) var(--space-3);
  background: var(--overlay-scrim);
  color: var(--color-contrast-ink);
}

.figure__scrim .placard {
  color: var(--color-contrast-ink);
}

.figure__scrim .placard__num {
  color: var(--color-contrast-accent);
}

.figure__caption {
  display: block;
  margin-top: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

/* ---------- surfaces & data ---------- */
.panel {
  background-color: var(--color-surface-alt);
  padding: var(--space-6);
}

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

.invert h1 { color: var(--color-contrast-ink); }
.invert h2 { color: var(--color-contrast-ink); }
.invert h3 { color: var(--color-contrast-ink); }

.invert a {
  color: var(--color-contrast-accent);
}

.slice-bottom {
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 72px), 0 100%);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.01em;
}

.data-table caption {
  text-align: left;
  padding-bottom: var(--space-2);
  font-family: var(--font-body);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.data-table th,
.data-table td {
  padding: var(--space-2) var(--space-3);
  text-align: left;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.data-table thead th {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.data-table tbody tr:nth-child(even) {
  background-color: var(--color-surface-deep);
}

/* ---------- folding ---------- */
.fold {
  border-top: var(--border-thin) solid var(--color-line);
}

.fold__trigger {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  width: 100%;
  padding: var(--space-3) 0;
  text-align: left;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  transition: color 0.18s ease-out;
}

.fold__trigger::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-primary);
  transition: transform 0.18s ease-out;
}

.fold__trigger[aria-expanded="true"]::after {
  content: "−";
}

.fold__trigger:hover {
  color: var(--color-primary);
}

.fold__panel {
  display: none;
  padding-bottom: var(--space-4);
}

.fold__panel.is-open {
  display: block;
}

/* ---------- round rail ---------- */
.round-rail {
  position: sticky;
  top: 120px;
  align-self: start;
  padding-left: var(--space-3);
  border-left: var(--border-thin) solid var(--color-line);
}

.round-rail__item {
  display: flex;
  gap: var(--space-2);
  align-items: baseline;
  padding-block: var(--space-1);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  transition: color 0.18s ease-out;
}

.round-rail__item:hover {
  color: var(--color-ink);
}

.round-rail__item[aria-current="true"] {
  color: var(--color-accent);
}

.round-rail__num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-primary);
}

.round-rail__item[aria-current="true"] .round-rail__num {
  color: var(--color-accent);
}

/* ---------- reveal ---------- */
html[data-motion="ready"] .reveal {
  transition: opacity 0.24s ease-out, transform 0.24s ease-out;
}

html[data-motion="ready"] .reveal:not(.is-in) {
  opacity: 0;
  transform: translateY(8px);
}

html[data-motion="ready"] .reveal.is-in {
  opacity: 1;
  transform: none;
}

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .site-header__inner {
    min-height: 66px;
    gap: var(--space-3);
  }

  .brand__mark { font-size: var(--text-base); }
  .brand__line { display: none; }

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

  .round-chip { display: none; }

  .site-nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    z-index: 130;
    width: min(84vw, 360px);
    margin: 0;
    padding: calc(var(--space-8) + var(--space-4)) var(--space-4) var(--space-6);
    background-color: var(--color-surface);
    border-left: var(--border-thin) solid var(--color-line);
    overflow-y: auto;
    transform: translateX(100%);
    transition: transform 0.2s ease-out;
  }

  .site-nav[data-open="true"] {
    transform: translateX(0);
  }

  .site-nav__list {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-4);
  }

  .site-nav__link {
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: var(--weight-heading);
    letter-spacing: -0.01em;
  }

  .site-nav__utility {
    display: block;
    margin-top: var(--space-6);
    padding-top: var(--space-4);
    border-top: var(--border-thin) solid var(--color-line);
    font-size: var(--text-xs);
    line-height: 1.8;
    letter-spacing: 0.06em;
    color: var(--color-ink-muted);
  }

  .site-footer { padding-block: var(--space-6) var(--space-4); }
  .site-footer__mark { font-size: var(--text-2xl); }
  .round-rail { position: static; }
}

@media (max-width: 640px) {
  .container,
  .site-header__inner,
  .site-footer__inner {
    width: min(var(--container), 100% - var(--space-4));
  }

  .section { padding-block: var(--space-8); }
  .section--lg { padding-block: var(--space-8); }

  .section-title { font-size: var(--text-xl); }
  .lead, .lede { font-size: var(--text-base); }

  .panel { padding: var(--space-4); }

  .data-table th,
  .data-table td { padding: var(--space-2); }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html[data-motion="ready"] .reveal,
  html[data-motion="ready"] .reveal:not(.is-in) {
    opacity: 1;
    transform: none;
  }
}