:root {
  --color-surface: #fefefe;
  --color-surface-alt: #f4f4f4;
  --color-surface-deep: #e6e6e6;
  --color-ink: #323639;
  --color-ink-soft: #5c6266;
  --color-ink-muted: #777e83;
  --color-line: #d9dadb;
  --color-primary: #0e7ab9;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #dcecf4;
  --color-accent: #167bb6;
  --color-accent-ink: #ffffff;
  --color-highlight: #d4e6f1;
  --color-focus: #0b78b7;
  --color-contrast-surface: #0e1a20;
  --color-contrast-ink: #e4e6e7;
  --color-contrast-line: #3d474c;
  --color-contrast-accent: #1b9ae4;
  --overlay-scrim: linear-gradient(180deg, rgba(14, 26, 32, 0.35) 0%, rgba(14, 26, 32, 0.72) 55%, rgba(14, 26, 32, 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: 12.9px;
  --text-sm: 16.1px;
  --text-base: 18px;
  --text-lg: 22.5px;
  --text-xl: 28.1px;
  --text-2xl: 35.2px;
  --text-3xl: 43.9px;
  --text-4xl: 54.9px;
  --text-display: clamp(34px, 6.2vw, 79px);
  --text-figure: clamp(28px, 4.5vw, 57px);
  --weight-heading: 793;
  --weight-body: 400;
  --leading-body: 1.79;
  --leading-heading: 1.15;
  --tracking-heading: -0.01em;
  --radius-sm: 2px;
  --radius-md: 4px;
  --radius-lg: 6px;
  --radius-pill: 6px;
  --border-thin: 2px;
  --border-thick: 3px;
  --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: 1000px;
  --measure: 64ch;
  --gutter: 24px;
  --section-y: 101px;
  --section-y-lg: 141px;
}

/* ============================================================
   1. 重置与中文排版
   ============================================================ */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 148px;
}

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);
  font-variant-numeric: tabular-nums;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  margin: 0 0 var(--space-2);
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
}

p { margin: 0 0 var(--space-3); }
p:last-child { margin-bottom: 0; }

ul,
ol { margin: 0 0 var(--space-3); padding-left: 1.25em; }
li { margin-bottom: 6px; }
li:last-child { margin-bottom: 0; }

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

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

a {
  color: var(--color-primary);
  text-decoration-line: underline;
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
}

a:hover { color: color-mix(in srgb, var(--color-primary) 78%, #000000); }

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

.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;
  border: 0;
}

/* ============================================================
   2. 布局容器与区块节奏
   ============================================================ */

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.section { padding: var(--section-y) 0; }
.section--tight { padding: var(--space-8) 0; }
.section--lg { padding: var(--section-y-lg) 0; }
.section--alt { background: var(--color-surface-alt); }
.section--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.section--deep h2,
.section--deep h3,
.section--deep h4 { color: var(--color-contrast-ink); }

.section__title {
  font-size: var(--text-xl);
  max-width: var(--measure);
  margin-bottom: var(--space-3);
}

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

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

.prose { max-width: var(--measure); }
.prose > p { margin-bottom: var(--space-3); }

.rule {
  height: 0;
  border: 0;
  border-top: var(--border-thin) solid var(--color-line);
  margin: var(--space-6) 0;
}

.eyebrow {
  display: inline-block;
  padding: 4px 12px;
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-base);
  font-weight: 600;
  letter-spacing: 0.04em;
  line-height: 1.4;
  margin-bottom: var(--space-3);
}

.eyebrow--inverse {
  background: var(--color-primary);
  color: var(--color-primary-ink);
}

.eyebrow--deep {
  border-color: var(--color-contrast-accent);
  background: transparent;
  color: var(--color-contrast-accent);
}

.display-title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  margin: 0 0 var(--space-3);
}

.data-figure {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
}

.figure-caption {
  display: block;
  margin-top: var(--space-1);
  font-size: var(--text-base);
  color: var(--color-ink-soft);
}

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

/* ============================================================
   3. 通用控件
   ============================================================ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  min-height: 48px;
  padding: 10px 20px;
  border: var(--border-thin) solid var(--color-primary);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  color: var(--color-primary);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: 600;
  line-height: 1.3;
  text-decoration: none;
  cursor: pointer;
  transition:
    background-color 120ms cubic-bezier(0.2, 0, 0.2, 1),
    color 120ms cubic-bezier(0.2, 0, 0.2, 1),
    border-color 120ms cubic-bezier(0.2, 0, 0.2, 1);
}

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

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

.btn--primary:hover {
  background: color-mix(in srgb, var(--color-primary) 86%, #000000);
  border-color: color-mix(in srgb, var(--color-primary) 86%, #000000);
  color: var(--color-primary-ink);
}

.btn--contrast {
  background: transparent;
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-ink);
}

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

.btn[aria-disabled="true"],
.btn:disabled {
  border-color: var(--color-surface-deep);
  background: var(--color-surface);
  color: var(--color-ink-muted);
  cursor: not-allowed;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px 12px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface-deep);
  color: var(--color-ink);
  font-size: var(--text-base);
  font-weight: 600;
  line-height: 1.4;
}

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

.tag--accent {
  border-color: var(--color-accent);
  background: var(--color-accent);
  color: var(--color-accent-ink);
}

.tag--contrast {
  border-color: var(--color-contrast-accent);
  background: transparent;
  color: var(--color-contrast-accent);
}

/* ============================================================
   4. 数据表格
   ============================================================ */

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-variant-numeric: tabular-nums;
}

.data-table caption {
  margin-bottom: var(--space-2);
  font-size: var(--text-base);
  color: var(--color-ink-soft);
  text-align: left;
}

.data-table th,
.data-table td {
  padding: 14px var(--space-2);
  text-align: left;
  border-bottom: var(--border-thin) solid var(--color-line);
  vertical-align: top;
}

.data-table th {
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
}

.data-table tbody tr:nth-child(even) { background: var(--color-surface-alt); }
.data-table tbody tr:hover { background: var(--color-primary-soft); }

.table-scroll {
  overflow-x: auto;
  scrollbar-color: var(--color-primary) var(--color-surface-deep);
}

/* ============================================================
   5. 图片区块容器（叠加深色遮罩，文字压在遮罩上）
   ============================================================ */

.media {
  position: relative;
  display: block;
  overflow: hidden;
  border-radius: var(--radius-sm);
  background: var(--color-contrast-surface);
  aspect-ratio: 16 / 9;
  width: 100%;
}

.media--wide { aspect-ratio: 21 / 9; }
.media--square { aspect-ratio: 1 / 1; }
.media--tall { aspect-ratio: 3 / 4; }

.media img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
}

.media__content {
  position: absolute;
  inset: auto 0 0 0;
  padding: var(--space-4) var(--space-3);
  color: var(--color-contrast-ink);
}

.media__content h2,
.media__content h3,
.media__content p { color: var(--color-contrast-ink); }

.media__content a {
  color: var(--color-contrast-accent);
  text-decoration-color: var(--color-contrast-accent);
}

/* ============================================================
   6. 面包屑
   ============================================================ */

.breadcrumb { margin: 0 0 var(--space-4); }

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: var(--text-base);
}

.breadcrumb__item {
  display: flex;
  align-items: center;
  margin: 0;
  color: var(--color-ink-muted);
}

.breadcrumb__item + .breadcrumb__item::before {
  content: "›";
  margin: 0 10px;
  color: var(--color-ink-muted);
}

.breadcrumb__link {
  color: var(--color-ink-soft);
  text-decoration: none;
}

.breadcrumb__link:hover {
  color: var(--color-primary);
  text-decoration: underline;
}

/* ============================================================
   7. 跳过链接
   ============================================================ */

.skip-link {
  position: absolute;
  top: -120px;
  left: var(--gutter);
  z-index: 200;
  padding: 12px 20px;
  border: var(--border-thick) solid var(--color-contrast-accent);
  border-radius: var(--radius-lg);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-base);
  font-weight: 600;
  text-decoration: none;
  transition: top 120ms cubic-bezier(0.2, 0, 0.2, 1);
}

.skip-link:focus {
  top: var(--space-3);
  color: var(--color-contrast-ink);
  outline: var(--border-thick) solid var(--color-focus);
  outline-offset: 2px;
}

/* ============================================================
   8. 站点头部
   ============================================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: var(--color-surface);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.site-header__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2) var(--space-3);
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: var(--space-3) var(--gutter);
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 2px;
  color: var(--color-ink);
  text-decoration: none;
  line-height: 1.2;
}

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

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
}

.brand__name strong { color: var(--color-primary); }

.brand__meta {
  font-family: var(--font-mono);
  font-size: var(--text-base);
  color: var(--color-ink-muted);
  letter-spacing: 0.02em;
}

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-height: 48px;
  margin-left: auto;
  padding: 10px 16px;
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  color: var(--color-ink);
  font-size: var(--text-base);
  font-weight: 600;
  cursor: pointer;
  transition:
    background-color 120ms cubic-bezier(0.2, 0, 0.2, 1),
    color 120ms cubic-bezier(0.2, 0, 0.2, 1),
    border-color 120ms cubic-bezier(0.2, 0, 0.2, 1);
}

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

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

.nav-toggle__bars {
  display: inline-flex;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 20px;
}

.nav-toggle__bars span {
  display: block;
  height: 2px;
  background: currentColor;
}

.nav { display: none; }

.nav[data-open] {
  display: block;
  flex-basis: 100%;
  width: 100%;
}

.nav__list {
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
  align-items: center;
  gap: var(--space-2);
  list-style: none;
  margin: 0;
  padding: var(--space-2) 0 var(--space-1);
  overflow-x: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--color-primary) var(--color-surface-deep);
}

.nav__item { margin: 0; }

.nav__link {
  display: inline-block;
  padding: 10px 14px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-lg);
  color: var(--color-ink);
  font-size: var(--text-base);
  font-weight: 600;
  line-height: 1.3;
  text-decoration: none;
  white-space: nowrap;
  transition:
    background-color 120ms cubic-bezier(0.2, 0, 0.2, 1),
    color 120ms cubic-bezier(0.2, 0, 0.2, 1),
    border-color 120ms cubic-bezier(0.2, 0, 0.2, 1);
}

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

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

.nav__link[aria-current="page"]:hover {
  background: color-mix(in srgb, var(--color-primary) 86%, #000000);
  border-color: color-mix(in srgb, var(--color-primary) 86%, #000000);
  color: var(--color-primary-ink);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-left: auto;
}

.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: -2px;
  height: var(--border-thick);
  background: var(--color-primary);
  transform: scaleX(0);
  transform-origin: 0 50%;
  will-change: transform;
}

/* ============================================================
   9. 站点页脚
   ============================================================ */

.site-footer {
  position: relative;
  margin-top: var(--section-y-lg);
  padding: var(--section-y) 0 var(--space-4);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.site-footer__inner {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 var(--gutter);
}

.site-footer__brand {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-4xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.site-footer__tagline {
  max-width: var(--measure);
  margin: 0 0 var(--space-6);
  font-size: var(--text-lg);
  line-height: var(--leading-body);
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6) var(--space-4);
  padding-top: var(--space-6);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.footer-block { min-width: 0; }

.footer-block__label {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-base);
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--color-contrast-accent);
}

.footer-block__list {
  display: grid;
  gap: 10px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-contrast-ink);
}

.footer-block__list li { margin: 0; }

.footer-link {
  color: var(--color-contrast-ink);
  text-decoration-color: var(--color-contrast-line);
  text-decoration-thickness: 2px;
  text-underline-offset: 4px;
}

.footer-link:hover {
  color: var(--color-contrast-accent);
  text-decoration-color: var(--color-contrast-accent);
}

.footer-num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--color-contrast-accent);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  margin-top: var(--space-8);
  padding-top: var(--space-4);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-base);
  color: var(--color-contrast-ink);
}

.footer-legal p { margin: 0; }

.footer-legal__icp {
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

.footer-legal__calibration { min-width: 0; }

.footer-legal__dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  margin-right: 10px;
  background: var(--color-contrast-accent);
  vertical-align: middle;
}

.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 70;
  min-height: 48px;
  padding: 10px 20px;
  border: var(--border-thin) solid var(--color-contrast-accent);
  border-radius: var(--radius-lg);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: 600;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition:
    opacity 120ms cubic-bezier(0.2, 0, 0.2, 1),
    transform 120ms cubic-bezier(0.2, 0, 0.2, 1),
    background-color 120ms cubic-bezier(0.2, 0, 0.2, 1),
    color 120ms cubic-bezier(0.2, 0, 0.2, 1);
}

.to-top[data-visible] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.to-top:hover {
  background: var(--color-contrast-accent);
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
}

/* ============================================================
   10. 断点
   ============================================================ */

@media (min-width: 720px) {
  .footer-grid { grid-template-columns: 1.4fr 1fr 1fr; }
}

@media (min-width: 960px) {
  .site-header__inner {
    padding: var(--space-3) var(--gutter);
  }

  .brand { flex: 0 0 auto; }

  .nav-toggle { display: none; }

  .nav {
    display: block;
    flex: 1 1 auto;
    min-width: 0;
  }

  .nav__list {
    flex-wrap: wrap;
    justify-content: center;
    padding: 0;
    overflow: visible;
  }

  .nav__link { padding: 10px 14px; }

  .header-actions { margin-left: 0; }
}

@media (max-width: 520px) {
  :root { --gutter: 20px; }

  .header-actions { width: 100%; }
  .header-actions .btn { width: 100%; }

  .site-footer__brand { font-size: var(--text-3xl); }

  .to-top {
    right: var(--space-2);
    bottom: var(--space-2);
    padding: 10px 16px;
  }
}

/* ============================================================
   11. 动效收敛
   ============================================================ */

@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;
    scroll-behavior: auto !important;
  }

  .to-top { transform: none; }
}