:root {
  --color-surface: #f7f7f7;
  --color-surface-alt: #efeeee;
  --color-surface-deep: #e3e2e2;
  --color-ink: #504444;
  --color-ink-soft: #786868;
  --color-ink-muted: #887877;
  --color-line: #d9d7d7;
  --color-primary: #db2524;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #f3dad9;
  --color-accent: #db2524;
  --color-accent-ink: #ffffff;
  --color-highlight: #f2d1d1;
  --color-focus: #da1715;
  --color-contrast-surface: #190d0d;
  --color-contrast-ink: #e7e4e4;
  --color-contrast-line: #463c3c;
  --color-contrast-accent: #e04342;
  --overlay-scrim: linear-gradient(180deg, rgba(25, 13, 13, 0.35) 0%, rgba(25, 13, 13, 0.72) 55%, rgba(25, 13, 13, 0.92) 100%);
  --font-heading: "Kaiti SC", STKaiti, KaiTi, "Songti SC", serif;
  --font-body: "Songti SC", "PingFang SC", "Microsoft YaHei", serif;
  --font-mono: ui-monospace, 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(34px, 6.4vw, 82px);
  --text-figure: clamp(28px, 4.6vw, 59px);
  --weight-heading: 591;
  --weight-body: 400;
  --leading-body: 1.93;
  --leading-heading: 1.19;
  --tracking-heading: 0.001em;
  --radius-sm: 2px;
  --radius-md: 2px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --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: 1080px;
  --measure: 59ch;
  --gutter: 24px;
  --section-y: 142px;
  --section-y-lg: 199px;
}

/* ============================================================
   01 · RESET
   ============================================================ */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body,
h1, h2, h3, h4, h5, h6,
p, figure, blockquote, dl, dd, ol, ul, address {
  margin: 0;
}

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

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

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

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

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

table { border-collapse: collapse; }

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

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

/* ============================================================
   02 · 中文排版基座
   ============================================================ */
body {
  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);
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  max-width: none;
}

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

strong, b { font-weight: var(--weight-heading); }

small { font-size: var(--text-xs); }

/* ============================================================
   03 · 通用工具
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

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

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
}

.eyebrow {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
  text-transform: uppercase;
}

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

.data-note {
  font-size: var(--text-xs);
  line-height: 1.7;
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

.display {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.08;
  letter-spacing: 0.006em;
}

.figure-num {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 400;
  line-height: 1.06;
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.012em;
}

/* 强调机制：色块高亮 / 朱红下划线 */
.mark {
  background-image: linear-gradient(transparent 60%, var(--color-highlight) 60%);
  background-repeat: no-repeat;
  background-size: 100% 100%;
  padding-inline: 0.08em;
}

.mark--underline {
  background-image: none;
  text-decoration: underline;
  text-decoration-color: var(--color-primary);
  text-decoration-thickness: 2px;
  text-underline-offset: 5px;
}

/* ============================================================
   04 · 分隔语言（印刷版面）
   ============================================================ */
.rule {
  display: block;
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  margin-block: var(--space-4);
  height: 0;
}

.rule--thick {
  border-top: calc(var(--border-thin) * 2) solid var(--color-ink);
}

.rule--double {
  border-top: var(--border-thin) solid var(--color-ink);
  border-bottom: var(--border-thin) solid var(--color-ink);
  height: 3px;
  margin-block: var(--space-4);
}

/* ============================================================
   05 · 按钮
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 9px 20px;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  line-height: 1.4;
  letter-spacing: 0.02em;
  color: var(--color-ink);
  background-color: transparent;
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-1);
  cursor: pointer;
  transition: background-color 160ms linear, color 160ms linear, border-color 160ms linear;
}

.btn:hover {
  background-color: var(--color-surface-deep);
}

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

.btn--primary:hover {
  background-color: color-mix(in srgb, var(--color-primary) 82%, #000000);
  border-color: color-mix(in srgb, var(--color-primary) 82%, #000000);
}

.btn--ghost {
  border-color: var(--color-line);
  color: var(--color-ink-soft);
}

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

/* ============================================================
   06 · 跳至正文
   ============================================================ */
.skip-link {
  position: fixed;
  top: -120px;
  left: var(--space-3);
  z-index: 200;
  padding: 10px 18px;
  font-size: var(--text-sm);
  color: var(--color-primary-ink);
  background-color: var(--color-primary);
  border-radius: var(--radius-sm);
  transition: top 160ms linear;
}

.skip-link:focus {
  top: var(--space-2);
}

/* ============================================================
   07 · 页头（框架式导航 / 数据条 / 品牌）
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 120;
  background-color: var(--color-surface);
  border-bottom: calc(var(--border-thin) * 2) solid var(--color-ink);
}

/* 数据条 */
.data-strip {
  background-color: var(--color-surface-deep);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.data-strip__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1) var(--space-4);
  min-height: 32px;
  padding-block: 4px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.03em;
  color: var(--color-ink-muted);
}

.data-strip__item {
  white-space: nowrap;
}

.data-strip__item b {
  font-weight: 400;
  color: var(--color-ink-soft);
}

/* 品牌行 */
.site-header__mast {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: var(--space-3);
}

.brand {
  display: flex;
  align-items: baseline;
  gap: var(--space-3);
  min-width: 0;
}

.brand__mark {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  line-height: 1.15;
  letter-spacing: 0.06em;
  color: var(--color-ink);
  white-space: nowrap;
}

.brand__tagline {
  font-size: var(--text-xs);
  line-height: 1.5;
  color: var(--color-ink-muted);
  letter-spacing: 0.03em;
}

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 8px 14px;
  font-size: var(--text-sm);
  color: var(--color-ink);
  background-color: transparent;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  transition: border-color 160ms linear, color 160ms linear;
}

.nav-toggle:hover { border-color: var(--color-ink); }

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 18px;
  height: 2px;
  background-color: currentColor;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 18px;
  height: 2px;
  background-color: currentColor;
}

.nav-toggle__bars::before { top: -5px; }
.nav-toggle__bars::after { top: 5px; }

.nav-toggle[aria-expanded="true"] {
  color: var(--color-primary);
  border-color: var(--color-primary);
}

/* 导航条 */
.site-nav {
  background-color: var(--color-surface-alt);
  border-top: var(--border-thin) solid var(--color-line);
}

.site-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding-block: var(--space-1);
}

.site-nav__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1) var(--space-4);
}

.site-nav__link {
  display: inline-block;
  padding-block: 6px;
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink-soft);
  border-bottom: 2px solid transparent;
  transition: color 160ms linear, border-color 160ms linear;
}

.site-nav__link:hover {
  color: var(--color-ink);
  border-bottom-color: var(--color-line);
}

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

.site-nav__cta { flex: 0 0 auto; }

/* ============================================================
   08 · 页脚
   ============================================================ */
.site-footer {
  margin-top: var(--section-y);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: calc(var(--border-thin) * 2) solid var(--color-contrast-line);
}

.site-footer h2,
.site-footer h3 {
  color: var(--color-contrast-ink);
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr)) minmax(0, 1.35fr);
  gap: var(--space-6) var(--space-4);
  padding-top: var(--section-y);
  padding-bottom: var(--space-8);
}

.footer-col__heading {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
  margin-bottom: var(--space-3);
  padding-bottom: var(--space-2);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.footer-col__list {
  display: grid;
  gap: var(--space-1);
}

.footer-col__list a {
  display: inline-block;
  padding-block: 3px;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent);
  border-bottom: var(--border-thin) solid transparent;
  transition: color 160ms linear, border-color 160ms linear;
}

.footer-col__list a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

.footer-contact {
  display: grid;
  gap: var(--space-3);
  font-style: normal;
}

.footer-contact__row {
  display: grid;
  gap: 3px;
}

.footer-contact__key {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 50%, transparent);
}

.footer-contact__val {
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-contrast-ink);
  overflow-wrap: anywhere;
}

.footer-bigtype {
  border-top: var(--border-thin) solid var(--color-contrast-line);
  padding-block: var(--space-6);
  overflow: hidden;
}

.footer-bigtype span {
  display: block;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: clamp(var(--text-2xl), 7.4vw, calc(var(--text-4xl) * 1.38));
  line-height: 1.1;
  letter-spacing: 0.012em;
  color: var(--color-contrast-ink);
  max-width: none;
}

.footer-bigtype em {
  font-style: normal;
  color: var(--color-contrast-accent);
}

.footer-legal {
  border-top: var(--border-thin) solid var(--color-contrast-line);
  padding-block: var(--space-3) var(--space-4);
  font-size: var(--text-xs);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent);
}

.footer-legal__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-1) var(--space-4);
}

.footer-legal__item {
  max-width: none;
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

/* ============================================================
   09 · 面包屑
   ============================================================ */
.breadcrumb {
  padding-block: var(--space-3);
  font-size: var(--text-xs);
  line-height: 1.6;
  color: var(--color-ink-muted);
  font-family: var(--font-mono);
  letter-spacing: 0.03em;
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 4px;
}

.breadcrumb__item a:hover { color: var(--color-ink); }

.breadcrumb__sep {
  color: var(--color-line);
  margin-inline: 2px;
}

.breadcrumb__item--current { color: var(--color-ink-soft); }

/* ============================================================
   10 · 章节 / 网格 / 深墨对照区
   ============================================================ */
.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--alt { background-color: var(--color-surface-alt); }
.section--deep { background-color: var(--color-surface-deep); }
.section--flush { padding-block: 0; }

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

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

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

.ink-band .rule,
.ink-band .rule--thick,
.ink-band .rule--double {
  border-color: var(--color-contrast-line);
}

.ink-band .eyebrow,
.ink-band .data-note { color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent); }

.ink-band .lede { color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent); }

.grid {
  display: grid;
  gap: var(--gutter);
}

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

/* ============================================================
   11 · 图录式图片容器
   ============================================================ */
.figure {
  display: block;
  margin: 0;
}

.figure__frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 3 / 2;
  background-color: var(--color-surface-deep);
  border-radius: var(--radius-sm);
}

.figure__frame--4x3 { aspect-ratio: 4 / 3; }
.figure__frame--1x1 { aspect-ratio: 1 / 1; }

.figure__frame img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.figure__scrim {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  gap: 4px;
  padding: var(--space-3);
  background-image: var(--overlay-scrim);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  line-height: 1.6;
}

.figure__scrim .figure__scrim-title {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: var(--leading-heading);
}

.figure__caption {
  margin-top: var(--space-2);
  font-size: var(--text-xs);
  line-height: 1.7;
  color: var(--color-ink-muted);
  max-width: none;
}

.ink-band .figure__frame { background-color: var(--color-contrast-line); }
.ink-band .figure__caption { color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent); }

/* ============================================================
   12 · 标签页 / 分段切换
   ============================================================ */
.tabs {
  display: block;
}

.tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 0;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.tabs__tab {
  padding: 10px 18px;
  margin-bottom: -1px;
  font-family: var(--font-body);
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink-muted);
  background-color: transparent;
  border: 0;
  border-bottom: 2px solid transparent;
  transition: color 160ms linear, border-color 160ms linear;
}

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

.tabs__tab[aria-selected="true"] {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.tabs__panel {
  padding-top: var(--space-3);
}

.tabs__panel[hidden] { display: none; }

.ink-band .tabs__list { border-bottom-color: var(--color-contrast-line); }
.ink-band .tabs__tab { color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent); }
.ink-band .tabs__tab[aria-selected="true"] {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}

/* ============================================================
   13 · 表格
   ============================================================ */
.table-wrap {
  overflow-x: auto;
  border-top: calc(var(--border-thin) * 2) solid var(--color-ink);
  border-bottom: var(--border-thin) solid var(--color-line);
  scrollbar-color: var(--color-ink-muted) var(--color-surface-deep);
  scrollbar-width: thin;
}

.table-wrap::-webkit-scrollbar { height: 8px; }
.table-wrap::-webkit-scrollbar-track { background-color: var(--color-surface-deep); }
.table-wrap::-webkit-scrollbar-thumb { background-color: var(--color-ink-muted); }

table.data {
  width: 100%;
  min-width: 620px;
  font-size: var(--text-sm);
  line-height: 1.6;
}

.data thead th {
  position: sticky;
  top: 0;
  z-index: 2;
  padding: 10px 14px;
  text-align: left;
  white-space: nowrap;
  font-family: var(--font-body);
  font-weight: var(--weight-heading);
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-soft);
  background-color: var(--color-surface-deep);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.data td {
  padding: 10px 14px;
  border-bottom: var(--border-thin) solid var(--color-line);
  vertical-align: top;
  max-width: none;
}

.data tbody tr:last-child td { border-bottom: 0; }

.data .num,
.data th.num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
  text-align: right;
  white-space: nowrap;
}

.data .sticky-col {
  position: sticky;
  left: 0;
  z-index: 1;
  background-color: var(--color-surface);
}

.ink-band .table-wrap { border-top-color: var(--color-contrast-line); }
.ink-band table.data { color: var(--color-contrast-ink); }
.ink-band .data thead th {
  background-color: var(--color-contrast-surface);
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent);
  border-bottom-color: var(--color-contrast-line);
}
.ink-band .data td { border-bottom-color: var(--color-contrast-line); }
.ink-band .data .sticky-col { background-color: var(--color-contrast-surface); }

/* ============================================================
   14 · 显现动效
   ============================================================ */
html.js [data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 240ms linear, transform 240ms linear;
}

html.js [data-reveal].is-revealed {
  opacity: 1;
  transform: none;
}

/* ============================================================
   15 · 响应式
   ============================================================ */
@media (max-width: 1000px) {
  .site-nav__list { gap: var(--space-1) var(--space-3); }
  .brand__tagline { display: none; }
}

@media (max-width: 900px) {
  .site-header { position: static; }

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

  .site-nav {
    display: none;
    border-top: var(--border-thin) solid var(--color-line);
  }

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

  .site-nav__inner {
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-3);
    padding-block: var(--space-3);
  }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .site-nav__list li { border-bottom: var(--border-thin) solid var(--color-line); }

  .site-nav__link {
    display: block;
    padding-block: 12px;
    border-bottom: 2px solid transparent;
  }

  .site-nav__list li:last-child .site-nav__link[aria-current="page"] { border-bottom-color: var(--color-primary); }

  .site-nav__cta { align-self: stretch; }

  .grid--2,
  .grid--3 { grid-template-columns: minmax(0, 1fr); }

  .footer-cols {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    padding-top: var(--space-8);
    gap: var(--space-6) var(--space-4);
  }

  .section { padding-block: calc(var(--section-y) * 0.52); }
  .section--lg { padding-block: calc(var(--section-y) * 0.72); }

  .site-footer { margin-top: calc(var(--section-y) * 0.6); }
}

@media (max-width: 640px) {
  :root { --gutter: 18px; }

  .data-strip__inner {
    gap: 2px var(--space-3);
    font-size: 11px;
    min-height: 28px;
  }

  .site-header__mast {
    align-items: flex-start;
    padding-block: var(--space-2);
  }

  .brand {
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
  }

  .brand__mark { font-size: var(--text-lg); }
  .brand__tagline { display: block; }

  .footer-cols { grid-template-columns: minmax(0, 1fr); }
  .footer-legal__inner { flex-direction: column; align-items: flex-start; }
}

/* ============================================================
   16 · 降级
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    transition-duration: 0.001ms !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
  }

  html.js [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
  }
}