:root {
  --color-surface: #fefefe;
  --color-surface-alt: #f5f5f6;
  --color-surface-deep: #e8e9ea;
  --color-ink: #494c55;
  --color-ink-soft: #6d717e;
  --color-ink-muted: #787c87;
  --color-line: #dddee0;
  --color-primary: #2956d6;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e0e6f8;
  --color-accent: #107d9d;
  --color-accent-ink: #ffffff;
  --color-highlight: #d3e7ed;
  --color-focus: #077ea1;
  --color-contrast-surface: #141825;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #424550;
  --color-contrast-accent: #18b8e7;
  --overlay-scrim: linear-gradient(180deg, rgba(20, 24, 37, 0.35) 0%, rgba(20, 24, 37, 0.72) 55%, rgba(20, 24, 37, 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: 11.4px;
  --text-sm: 14.3px;
  --text-base: 16px;
  --text-lg: 20.0px;
  --text-xl: 25.0px;
  --text-2xl: 31.2px;
  --text-3xl: 39.1px;
  --text-4xl: 48.8px;
  --text-display: clamp(38px, 7.8vw, 100px);
  --text-figure: clamp(32px, 5.6vw, 72px);
  --weight-heading: 705;
  --weight-body: 400;
  --leading-body: 1.73;
  --leading-heading: 1.18;
  --tracking-heading: 0.011em;
  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 1px;
  --radius-pill: 1px;
  --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: 74ch;
  --gutter: 24px;
  --section-y: 80px;
  --section-y-lg: 112px;
}

/* ============================================================
   01 · 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;
}

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

button, input, select, textarea { font: inherit; color: inherit; border-radius: var(--radius-sm); }

button { cursor: pointer; }

table { border-collapse: collapse; width: 100%; }

/* ============================================================
   02 · 中文排版
   ============================================================ */
h1, h2, h3, h4, h5, h6 {
  margin: 0 0 var(--space-2);
  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-4xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }
h5, h6 { font-size: var(--text-base); }

p { margin: 0 0 var(--space-2); max-width: var(--measure); }

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

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

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

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

code, kbd, samp { font-family: var(--font-mono); font-size: 0.94em; letter-spacing: 0.04em; }

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

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

/* ============================================================
   03 · 容器与工具类
   ============================================================ */
.container {
  width: min(100% - (var(--gutter) * 2), var(--container));
  margin-inline: auto;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: -80px;
  left: var(--space-2);
  z-index: 200;
  padding: 10px 16px;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-accent);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  text-decoration: none;
  transition: top 140ms linear;
}

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

/* ============================================================
   04 · 报头
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 90;
  background: var(--color-surface);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.scroll-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: var(--color-line);
  overflow: hidden;
  pointer-events: none;
}

.scroll-progress__bar {
  display: block;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-accent) 100%);
  transform: scaleX(0);
  transform-origin: 0 50%;
}

.header-masthead {
  background-image: linear-gradient(
    90deg,
    color-mix(in srgb, var(--color-line) 42%, transparent) 1px,
    transparent 1px
  );
  background-size: 24px 100%;
  background-repeat: repeat-x;
}

.masthead-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: var(--space-3);
  padding-block: var(--space-3);
  transition: padding 200ms linear;
}

.coord-tag {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  white-space: nowrap;
}

.coord-tag--start { justify-self: start; }
.coord-tag--end { justify-self: end; }

.brand { text-align: center; min-width: 0; }

.brand__link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  color: var(--color-ink);
  text-decoration: none;
}

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

.brand__mark {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border: var(--border-thin) solid var(--color-primary);
  color: var(--color-primary);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  line-height: 1;
}

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

.brand__tagline {
  margin: 6px 0 0;
  max-width: none;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

.brand__meta {
  margin: 2px 0 0;
  max-width: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.header-nav {
  position: relative;
  border-top: var(--border-thin) dotted var(--color-line);
}

.nav-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 54px;
}

.nav { display: block; }

.nav__list {
  display: flex;
  align-items: center;
  gap: clamp(14px, 2.6vw, 34px);
  flex-wrap: wrap;
  justify-content: center;
}

.nav__link {
  display: inline-block;
  padding: 16px 2px;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-ink-soft);
  border-bottom: var(--border-thin) solid transparent;
  text-decoration: none;
  transition: color 140ms linear, border-color 140ms linear;
}

.nav__link:hover {
  color: var(--color-primary);
  border-bottom: var(--border-thin) dotted var(--color-primary);
  text-decoration: none;
}

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

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 9px 12px;
  background: var(--color-surface);
  border: var(--border-thin) dotted var(--color-line);
  color: var(--color-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
}

.nav-toggle::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1;
  color: var(--color-primary);
}

.nav-toggle[aria-expanded="true"]::after { content: "–"; }

.site-header[data-compact="true"] .masthead-grid { padding-block: var(--space-1); }

.site-header[data-compact="true"] .brand__tagline,
.site-header[data-compact="true"] .brand__meta { display: none; }

/* ============================================================
   05 · 页脚
   ============================================================ */
.site-footer {
  background-color: var(--color-contrast-surface);
  background-image: radial-gradient(
    color-mix(in srgb, var(--color-contrast-line) 62%, transparent) 1px,
    transparent 1px
  );
  background-size: 32px 32px;
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1.3fr 1.45fr;
  padding-block: var(--section-y) var(--space-8);
}

.footer-grid > * { padding-right: var(--space-3); }

.footer-grid > * + * {
  border-left: var(--border-thin) dotted var(--color-contrast-line);
  padding-left: var(--space-3);
}

.footer-brand__link {
  display: block;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-xl);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
  text-decoration: none;
}

.footer-brand__link:hover { color: var(--color-contrast-accent); text-decoration: none; }

.footer-coord {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 var(--space-2);
  max-width: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-contrast-accent);
}

.footer-coord::before {
  content: "";
  width: 8px;
  height: 8px;
  background: var(--color-contrast-accent);
}

.footer-brand__line {
  margin: var(--space-1) 0 0;
  max-width: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.footer-brand__note {
  margin: var(--space-2) 0 0;
  max-width: none;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}

.footer-col__title {
  display: block;
  margin: 0 0 var(--space-2);
  padding-bottom: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.08em;
  color: var(--color-contrast-accent);
  border-bottom: var(--border-thin) dotted var(--color-contrast-line);
}

.footer-list {
  display: grid;
  gap: 8px;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
}

.footer-list a {
  color: var(--color-contrast-ink);
  text-decoration: none;
  border-bottom: var(--border-thin) dotted transparent;
  padding-bottom: 1px;
  transition: color 140ms linear, border-color 140ms linear;
}

.footer-list a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
  text-decoration: none;
}

.footer-list--plain li {
  line-height: 1.7;
  max-width: none;
  color: color-mix(in srgb, var(--color-contrast-ink) 86%, transparent);
}

.subscribe__note {
  margin: 0 0 var(--space-2);
  max-width: none;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
}

.subscribe__row {
  display: flex;
  border: var(--border-thin) dotted var(--color-contrast-line);
}

.subscribe__input {
  flex: 1 1 auto;
  min-width: 0;
  padding: 11px 12px;
  background: color-mix(in srgb, var(--color-contrast-ink) 7%, transparent);
  border: 0;
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
}

.subscribe__input::placeholder {
  color: color-mix(in srgb, var(--color-contrast-ink) 52%, transparent);
}

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

.subscribe__btn {
  flex: 0 0 auto;
  padding: 11px 16px;
  background: var(--color-contrast-accent);
  border: 0;
  border-left: var(--border-thin) dotted var(--color-contrast-line);
  color: var(--color-contrast-surface);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  transition: background-color 140ms linear;
}

.subscribe__btn:hover {
  background: color-mix(in srgb, var(--color-contrast-accent) 78%, var(--color-contrast-ink));
}

.subscribe__status {
  margin: var(--space-1) 0 0;
  min-height: 18px;
  max-width: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: color-mix(in srgb, var(--color-contrast-ink) 70%, transparent);
}

.subscribe__status[data-state="ok"] { color: var(--color-contrast-accent); }

.subscribe__status[data-state="error"] { color: var(--color-highlight); }

.footer-legal {
  border-top: var(--border-thin) dotted var(--color-contrast-line);
  background: color-mix(in srgb, var(--color-contrast-surface) 93%, var(--color-primary));
}

.footer-legal__row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding-block: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent);
}

.footer-legal__nav {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.footer-legal__nav a {
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
  text-decoration: none;
  border-bottom: var(--border-thin) dotted transparent;
  padding-bottom: 1px;
}

.footer-legal__nav a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
  text-decoration: none;
}

/* ============================================================
   06 · 区块与展现
   ============================================================ */
.section {
  position: relative;
  padding-block: var(--section-y);
  border-top: var(--border-thin) dotted var(--color-line);
}

.section--lg { padding-block: var(--section-y-lg); }
.section--flush { border-top: 0; }

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

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

.section--deep p { color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent); }

[data-section] { position: relative; }

[data-section]::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  width: 100%;
  height: 1px;
  background-image: repeating-linear-gradient(
    90deg,
    var(--color-primary) 0 6px,
    transparent 6px 12px
  );
  transform: scaleX(0);
  transform-origin: 0 50%;
  transition: transform 220ms linear;
  pointer-events: none;
}

[data-section].is-revealed::before { transform: scaleX(1); }

.section-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: baseline;
  gap: var(--space-2) var(--space-3);
  margin-bottom: var(--space-4);
}

.section-head__coord {
  display: inline-block;
  padding: 3px 7px;
  border: var(--border-thin) solid var(--color-primary);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.2;
  letter-spacing: 0.08em;
}

.section-head__title { margin: 0; font-size: var(--text-2xl); }

.section-head__note {
  grid-column: 2;
  margin: 0;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

/* ============================================================
   07 · 页面头与面包屑
   ============================================================ */
.page-head {
  padding-block: var(--space-6) var(--space-4);
  border-bottom: var(--border-thin) dotted var(--color-line);
}

.page-head__coord {
  display: block;
  margin-bottom: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.page-head__title { margin: 0 0 var(--space-2); font-size: var(--text-4xl); }

.page-head__lede {
  margin: 0;
  font-size: var(--text-lg);
  color: var(--color-ink-soft);
}

.breadcrumb { border-bottom: var(--border-thin) dotted var(--color-line); }

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  padding-block: 12px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.breadcrumb__item { display: inline-flex; align-items: center; }

.breadcrumb__item + .breadcrumb__item::before {
  content: "/";
  padding-inline: var(--space-1);
  color: var(--color-line);
}

.breadcrumb__item a { color: var(--color-ink-soft); text-decoration: none; }
.breadcrumb__item a:hover { color: var(--color-primary); }

/* ============================================================
   08 · 栅格与衬底块
   ============================================================ */
.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)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid--asym-5-7 { grid-template-columns: 5fr 7fr; }
.grid--asym-7-5 { grid-template-columns: 7fr 5fr; }
.grid--asym-8-4 { grid-template-columns: 8fr 4fr; }

.panel {
  background: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  padding: var(--space-3);
}

.panel--soft {
  background: var(--color-primary-soft);
  border-color: color-mix(in srgb, var(--color-primary) 30%, transparent);
}

.panel--accent {
  background: var(--color-highlight);
  border-color: var(--color-accent);
}

.panel--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-color: var(--color-contrast-line);
}

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

/* ============================================================
   09 · 索引表
   ============================================================ */
.table-scroll { overflow-x: auto; }

.index-table { min-width: 620px; font-size: var(--text-sm); }

.index-table th {
  padding: 10px 12px;
  text-align: left;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  background: var(--color-surface-deep);
  border-bottom: var(--border-thin) dotted var(--color-line);
}

.index-table td {
  padding: 12px;
  vertical-align: top;
  border-bottom: var(--border-thin) dotted var(--color-line);
  color: var(--color-ink);
}

.index-table tbody tr:hover td { background: var(--color-surface-alt); }

/* ============================================================
   10 · 正文与按钮
   ============================================================ */
.prose { max-width: var(--measure); }

.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 { margin: 0 0 var(--space-2); padding-left: 1.3em; list-style: disc; max-width: var(--measure); }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: 8px; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 12px 20px;
  background: transparent;
  border: var(--border-thin) solid var(--color-ink);
  border-radius: var(--radius-sm);
  color: var(--color-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  text-decoration: none;
  transition: background-color 150ms linear, color 150ms linear, border-color 150ms linear;
}

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

.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) 82%, var(--color-contrast-surface)); }

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

.btn--accent:hover { background: color-mix(in srgb, var(--color-accent) 82%, var(--color-contrast-surface)); }

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

.btn--ghost:hover { border-color: var(--color-primary); color: var(--color-primary); }

/* ============================================================
   11 · 图片容器（图纸样张）
   ============================================================ */
.figure {
  margin: 0;
  padding: var(--space-1);
  background: var(--color-surface-deep);
  border: var(--border-thin) solid var(--color-line);
}

.figure__frame {
  position: relative;
  display: block;
  width: 100%;
  aspect-ratio: 16 / 7;
  background: var(--color-surface-deep);
  overflow: hidden;
}

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

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

.figure__caption {
  padding: var(--space-1) 2px 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

/* ============================================================
   12 · 坐标轨与进度（滚动高亮）
   ============================================================ */
.coord-rail {
  position: fixed;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  z-index: 40;
  display: none;
  gap: 10px;
  padding: var(--space-2) 12px var(--space-2) 14px;
  background: color-mix(in srgb, var(--color-surface) 90%, transparent);
  border-right: var(--border-thin) dotted var(--color-line);
}

.coord-rail__item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  transition: color 140ms linear;
}

.coord-rail__item::before {
  content: "";
  width: 10px;
  height: 1px;
  background: currentColor;
  transition: width 140ms linear;
}

.coord-rail__item.is-current { color: var(--color-primary); }
.coord-rail__item.is-current::before { width: 22px; }

@media (min-width: 1480px) {
  .coord-rail { display: grid; }
}

/* ============================================================
   13 · 响应式
   ============================================================ */
@media (max-width: 1024px) {
  .footer-grid { grid-template-columns: 1fr 1fr; gap: var(--space-4) 0; }
  .footer-grid > * + * { border-left: 0; padding-left: 0; }
  .footer-grid > *:nth-child(even) {
    border-left: var(--border-thin) dotted var(--color-contrast-line);
    padding-left: var(--space-3);
  }
}

@media (max-width: 900px) {
  .masthead-grid {
    grid-template-columns: 1fr;
    gap: var(--space-1);
    padding-block: var(--space-2);
  }

  .coord-tag--start { justify-self: center; text-align: center; }
  .coord-tag--end { display: none; }

  .nav-row {
    justify-content: flex-end;
    min-height: 48px;
  }

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

  .nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    padding: var(--space-1) var(--gutter) var(--space-2);
    background: var(--color-surface);
    border-bottom: var(--border-thin) solid var(--color-line);
    border-top: var(--border-thin) dotted var(--color-line);
    box-shadow: var(--shadow-1);
    z-index: 95;
  }

  .nav[data-open="true"] { display: block; }

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

  .nav__link {
    padding: 14px 0;
    font-size: var(--text-base);
    border-bottom: var(--border-thin) dotted var(--color-line);
    border-left: 0;
  }

  .nav__link:last-child { border-bottom: 0; }

  .grid--2,
  .grid--3,
  .grid--4,
  .grid--asym-5-7,
  .grid--asym-7-5,
  .grid--asym-8-4 { grid-template-columns: minmax(0, 1fr); }

  .section-head { grid-template-columns: minmax(0, 1fr); }
  .section-head__note { grid-column: 1; }
}

@media (max-width: 640px) {
  .footer-grid { grid-template-columns: 1fr; gap: 0; }

  .footer-grid > *,
  .footer-grid > *:nth-child(even) {
    border-left: 0;
    padding-left: 0;
  }

  .footer-grid > * + * {
    margin-top: var(--space-3);
    border-top: var(--border-thin) dotted var(--color-contrast-line);
    padding-top: var(--space-3);
  }

  .subscribe__row { flex-direction: column; }

  .subscribe__btn { border-left: 0; border-top: var(--border-thin) dotted var(--color-contrast-line); }

  .footer-legal__row { justify-content: flex-start; }
}

/* ============================================================
   14 · 动效降级
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

  html { scroll-behavior: auto; }

  [data-section]::before { transform: scaleX(1); }
}