/* ==========================================================================
   /assets/site.css — 皇家国际娱乐 · 共享外壳
   工程蓝图骨架 + 深色厅廊仪式感
   ========================================================================== */

/* ---------- 0. 设计变量（定稿，原样使用） ---------- */
:root {
  --color-surface: #f8f8f9;
  --color-surface-alt: #efeff0;
  --color-surface-deep: #e2e3e4;
  --color-ink: #40484e;
  --color-ink-soft: #646e77;
  --color-ink-muted: #768089;
  --color-line: #d7d8da;
  --color-primary: #2c79bf;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #dbe6f1;
  --color-accent: #2238dd;
  --color-accent-ink: #ffffff;
  --color-highlight: #d1d5f4;
  --color-focus: #152eea;
  --color-contrast-surface: #19232c;
  --color-contrast-ink: #e4e6e7;
  --color-contrast-line: #464e55;
  --color-contrast-accent: #7280e9;
  --overlay-scrim: linear-gradient(180deg, rgba(25, 35, 44, 0.35) 0%, rgba(25, 35, 44, 0.72) 55%, rgba(25, 35, 44, 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: 13.7px;
  --text-base: 15px;
  --text-lg: 18.0px;
  --text-xl: 21.6px;
  --text-2xl: 25.9px;
  --text-3xl: 31.1px;
  --text-4xl: 37.3px;
  --text-display: clamp(34px, 5.7vw, 73px);
  --text-figure: clamp(28px, 4.1vw, 53px);
  --weight-heading: 682;
  --weight-body: 400;
  --leading-body: 1.8;
  --leading-heading: 1.19;
  --tracking-heading: 0.015em;
  --radius-sm: 1px;
  --radius-md: 2px;
  --radius-lg: 2px;
  --radius-pill: 2px;
  --border-thin: 1px;
  --border-thick: 2px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 7px;
  --space-2: 14px;
  --space-3: 21px;
  --space-4: 28px;
  --space-6: 42px;
  --space-8: 56px;
  --container: 1300px;
  --measure: 71ch;
  --gutter: 28px;
  --section-y: 73px;
  --section-y-lg: 102px;
}

/* ---------- 1. Reset 与基础排版 ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

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

body {
  margin: 0;
  min-height: 100%;
  color: var(--color-ink);
  background-color: var(--color-surface);
  background-image:
    linear-gradient(to right, color-mix(in srgb, var(--color-line) 42%, transparent) 1px, transparent 1px),
    linear-gradient(to bottom, color-mix(in srgb, var(--color-line) 42%, transparent) 1px, transparent 1px);
  background-size: calc(var(--space-8) * 2) calc(var(--space-8) * 2);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
}

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

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

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

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

p { margin: 0; }

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

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

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

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

/* ---------- 2. 通用工具与结构 ---------- */
.shell {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-4);
}

.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);
}

.span-2 { grid-column: span 2; }
.span-3 { grid-column: span 3; }
.span-4 { grid-column: span 4; }
.span-5 { grid-column: span 5; }
.span-6 { grid-column: span 6; }
.span-7 { grid-column: span 7; }
.span-8 { grid-column: span 8; }
.span-9 { grid-column: span 9; }
.span-10 { grid-column: span 10; }
.span-12 { grid-column: span 12; }

.stack > * + * { margin-top: var(--space-3); }

.mono,
.mono-label,
.coord { font-family: var(--font-mono); letter-spacing: 0.08em; }

.mono-label {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  text-transform: uppercase;
}

.coord {
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.coord-on-dark { color: var(--color-contrast-accent); }

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

.mark {
  padding: 0 2px;
  background-image: linear-gradient(transparent 60%, var(--color-highlight) 60%);
}

.mark-line {
  border-bottom: var(--border-thin) solid var(--color-primary);
  padding-bottom: 1px;
}

.rule-dotted {
  margin-block: var(--space-4);
  border: 0;
  border-top: var(--border-thin) dotted var(--color-line);
}

.ticks {
  height: 7px;
  background-image: repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 14px);
}

/* ---------- 3. 头部命令栏 ---------- */
.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -110px;
  z-index: 200;
  padding: 9px 14px;
  border-radius: var(--radius-md);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-size: var(--text-sm);
  transition: top 0.18s ease;
}

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

.scroll-progress {
  position: fixed;
  inset: 0 0 auto 0;
  height: 2px;
  z-index: 120;
  background: color-mix(in srgb, var(--color-contrast-surface) 55%, transparent);
  pointer-events: none;
}

.scroll-progress-bar {
  display: block;
  width: 100%;
  height: 100%;
  background: var(--color-accent);
  transform: scaleX(0);
  transform-origin: 0 50%;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 80;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
}

.site-header::after {
  content: "";
  display: block;
  height: 6px;
  opacity: 0.85;
  background-image: repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 15px);
}

.site-header[data-scrolled="true"] { border-bottom-color: var(--color-contrast-accent); }

.header-shell {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  min-height: 70px;
  transition: min-height 0.2s ease;
}

.site-header[data-scrolled="true"] .header-shell { min-height: 58px; }

/* 品牌 */
.brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex: 0 0 auto;
  padding-block: var(--space-2);
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border: var(--border-thin) solid var(--color-contrast-accent);
  border-radius: var(--radius-md);
  background: color-mix(in srgb, var(--color-contrast-accent) 14%, transparent);
  color: var(--color-contrast-accent);
  font-family: var(--font-mono);
  font-size: var(--text-lg);
}

.brand-text { display: flex; flex-direction: column; gap: 1px; }

.brand-name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.brand-sub {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
}

.brand-version {
  align-self: center;
  margin-left: var(--space-1);
  padding: 2px 7px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-sm);
  color: var(--color-contrast-accent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
}

/* 导航 */
.site-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: var(--space-3);
  flex: 1 1 auto;
  margin-left: auto;
}

.nav-list { display: flex; align-items: stretch; flex-wrap: wrap; }

.nav-item { display: flex; }

.nav-link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding: 10px 12px;
  border-left: var(--border-thin) dotted var(--color-contrast-line);
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
  font-size: var(--text-sm);
  transition: color 0.18s ease, background-color 0.18s ease;
}

.nav-item:last-child .nav-link { border-right: var(--border-thin) dotted var(--color-contrast-line); }

.nav-link:hover,
.nav-link:focus-visible {
  color: var(--color-contrast-ink);
  background: color-mix(in srgb, var(--color-contrast-accent) 14%, transparent);
}

.nav-index {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
}

.nav-text { letter-spacing: 0.02em; }

.nav-link[aria-current="page"] {
  color: var(--color-contrast-ink);
  background: color-mix(in srgb, var(--color-contrast-accent) 20%, transparent);
}

.nav-link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 4px;
  height: var(--border-thick);
  background: var(--color-contrast-accent);
}

.nav-link[aria-current="page"] .nav-index { color: var(--color-contrast-ink); }

.nav-link[aria-current="page"] .nav-index::before {
  content: "";
  display: inline-block;
  width: 5px;
  height: 5px;
  margin-right: 5px;
  vertical-align: middle;
  border-radius: 50%;
  background: var(--color-contrast-accent);
}

.nav-meta { display: none; }

/* 头部右侧 */
.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  flex: 0 0 auto;
}

.header-notice {
  display: none;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: color-mix(in srgb, var(--color-contrast-ink) 64%, transparent);
}

.header-notice .mono-label { color: var(--color-contrast-accent); }

.cmd-cta { font-size: var(--text-sm); }

.nav-toggle { display: none; }

@media (min-width: 1200px) {
  .header-notice { display: inline-flex; }
}

/* ---------- 4. 页脚 ---------- */
.site-footer {
  margin-top: var(--section-y);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.site-footer::before {
  content: "";
  display: block;
  height: 6px;
  opacity: 0.85;
  background-image: repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 15px);
}

.footer-shell { padding-block: var(--space-6) var(--space-4); }

.footer-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.5fr);
  gap: var(--space-4);
  padding-bottom: var(--space-4);
  border-bottom: var(--border-thin) dotted var(--color-contrast-line);
}

.footer-brand { display: grid; gap: 4px; justify-items: start; }

.footer-mark {
  display: grid;
  place-items: center;
  width: 32px;
  height: 32px;
  margin-bottom: var(--space-1);
  border: var(--border-thin) solid var(--color-contrast-accent);
  border-radius: var(--radius-md);
  background: color-mix(in srgb, var(--color-contrast-accent) 14%, transparent);
  color: var(--color-contrast-accent);
  font-family: var(--font-mono);
  font-size: var(--text-base);
}

.footer-name {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  letter-spacing: var(--tracking-heading);
}

.footer-version {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent);
}

.footer-version b { color: var(--color-contrast-accent); }

.footer-statement {
  max-width: var(--measure);
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, transparent);
}

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

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

.footer-col-title {
  display: flex;
  align-items: baseline;
  gap: 8px;
  margin-bottom: var(--space-2);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  color: var(--color-contrast-ink);
}

.footer-col-index {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-contrast-accent);
}

.footer-list { display: grid; gap: 7px; }

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

.footer-link {
  display: inline-block;
  padding-bottom: 1px;
  border-bottom: var(--border-thin) dotted transparent;
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
  font-size: var(--text-sm);
  transition: color 0.18s ease, border-color 0.18s ease;
}

.footer-link:hover,
.footer-link:focus-visible {
  color: var(--color-contrast-ink);
  border-bottom-color: var(--color-contrast-accent);
}

.footer-note {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.75;
  color: color-mix(in srgb, var(--color-contrast-ink) 60%, transparent);
  word-break: break-word;
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-4);
  padding-top: var(--space-3);
  border-top: var(--border-thin) dotted var(--color-contrast-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.footer-icp { color: var(--color-contrast-accent); }

/* ---------- 5. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 9px 16px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
  color: var(--color-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}

.btn:hover { background: var(--color-primary-soft); border-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) 80%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-primary) 80%, 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));
  border-color: color-mix(in srgb, var(--color-accent) 82%, var(--color-contrast-surface));
}

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

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

.btn-quiet:hover {
  background: color-mix(in srgb, var(--color-contrast-accent) 22%, transparent);
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-ink);
}

.btn-link {
  padding: 0;
  border: 0;
  background: none;
  color: var(--color-primary);
  border-bottom: var(--border-thin) solid var(--color-primary);
}

.btn-link:hover { color: var(--color-accent); border-bottom-color: var(--color-accent); }

/* ---------- 6. 面包屑 ---------- */
.crumbs {
  padding-block: var(--space-2);
  border-bottom: var(--border-thin) dotted var(--color-line);
}

.crumbs-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.crumbs-item { display: inline-flex; align-items: center; gap: var(--space-2); }

.crumbs-sep { color: var(--color-line); }

.crumbs-current { color: var(--color-accent); }

/* ---------- 7. 区块头 / 面板 / 徽章 ---------- */
.sec-head {
  margin-bottom: var(--space-4);
  padding-top: var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
}

.sec-index {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-primary);
}

.sec-title {
  margin-top: var(--space-1);
  font-size: var(--text-3xl);
}

.sec-note {
  margin-top: var(--space-2);
  max-width: var(--measure);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

.panel {
  padding: var(--space-4);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface);
}

.panel-alt { background: var(--color-surface-alt); }
.panel-deep { background: var(--color-surface-deep); }

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

.panel-dark .sec-head { border-top-color: var(--color-contrast-line); }
.panel-dark .sec-index { color: var(--color-contrast-accent); }
.panel-dark .sec-note { color: color-mix(in srgb, var(--color-contrast-ink) 76%, transparent); }

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
}

.badge-accent {
  border-color: var(--color-accent);
  background: color-mix(in srgb, var(--color-accent) 8%, transparent);
  color: var(--color-accent);
}

.badge-dark {
  border-color: var(--color-contrast-line);
  background: transparent;
  color: var(--color-contrast-accent);
}

/* ---------- 8. 表格 ---------- */
.table-wrap {
  overflow-x: auto;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface);
}

.tbl {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
}

.tbl th,
.tbl td {
  padding: 9px 12px;
  text-align: left;
  vertical-align: top;
  border-bottom: var(--border-thin) dotted var(--color-line);
}

.tbl th {
  background: var(--color-surface-deep);
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-soft);
  white-space: nowrap;
}

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

/* ---------- 9. 图片容器 ---------- */
.figure {
  position: relative;
  margin: 0;
  overflow: hidden;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-deep);
}

.figure img {
  width: 100%;
  height: 100%;
  aspect-ratio: var(--figure-ratio, 16 / 9);
  object-fit: cover;
}

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

.figure-frame::after {
  content: "";
  position: absolute;
  inset: 7px;
  border: var(--border-thin) dotted color-mix(in srgb, var(--color-contrast-ink) 45%, transparent);
  pointer-events: none;
}

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

.media-text {
  position: absolute;
  inset: auto 0 0 0;
  z-index: 2;
  padding: var(--space-3);
  color: var(--color-contrast-ink);
}

.figure-caption {
  margin-top: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

/* ---------- 10. 可展开内容组 ---------- */
.expander { border-top: var(--border-thin) dotted var(--color-line); }

.expander > summary {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  padding: var(--space-3) 0;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--text-lg);
  color: var(--color-ink);
}

.expander > summary::-webkit-details-marker { display: none; }

.expander > summary::before {
  content: "＋";
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-primary);
}

.expander[open] > summary::before { content: "－"; color: var(--color-accent); }

.expander[open] > summary { color: var(--color-accent); }

.expander-body {
  padding: 0 0 var(--space-4);
  max-width: var(--measure);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

/* ---------- 11. 章节索引 / 旁注 ---------- */
.side-index {
  position: sticky;
  top: calc(70px + var(--space-4));
  padding-left: var(--space-3);
  border-left: var(--border-thin) dotted var(--color-line);
}

.side-index-title {
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-primary);
}

.index-link {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: 7px 0;
  border-bottom: var(--border-thin) dotted var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
  transition: color 0.18s ease;
}

.index-link::before {
  content: "";
  flex: 0 0 auto;
  width: 5px;
  height: 5px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: 50%;
}

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

.index-link.is-active { color: var(--color-accent); }

.index-link.is-active::before {
  background: var(--color-accent);
  border-color: var(--color-accent);
}

.aside-note {
  padding-left: var(--space-3);
  border-left: var(--border-thin) solid var(--color-primary);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

/* ---------- 12. 显现动效 ---------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

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

/* ---------- 13. 响应式 ---------- */
@media (max-width: 1200px) {
  .nav-link { padding: 10px 9px; }
  .header-shell { gap: var(--space-3); }
}

@media (max-width: 1024px) {
  .span-3,
  .span-4 { grid-column: span 6; }

  .span-5,
  .span-7,
  .span-8,
  .span-9,
  .span-10 { grid-column: span 12; }

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

@media (max-width: 960px) {
  body { padding-bottom: 64px; }

  .header-shell { min-height: 58px; gap: var(--space-2); }
  .brand-version { display: none; }
  .header-actions { display: none; }

  .site-nav {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 56px;
    z-index: 94;
    display: block;
    max-height: 70vh;
    overflow-y: auto;
    margin: 0;
    padding: var(--space-3) var(--space-4) var(--space-6);
    background: var(--color-contrast-surface);
    border-top: var(--border-thin) solid var(--color-contrast-line);
    opacity: 0;
    visibility: hidden;
    transform: translateY(14px);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
  }

  .site-nav[data-open="true"] {
    opacity: 1;
    visibility: visible;
    transform: none;
  }

  .nav-list { flex-direction: column; width: 100%; }

  .nav-item { width: 100%; }

  .nav-link {
    width: 100%;
    justify-content: space-between;
    padding: 13px 0;
    border-left: 0;
    border-bottom: var(--border-thin) dotted var(--color-contrast-line);
    font-size: var(--text-lg);
  }

  .nav-item:last-child .nav-link { border-right: 0; }

  .nav-link[aria-current="page"] { padding-inline: 10px; }

  .nav-link[aria-current="page"]::after { left: 10px; right: 10px; bottom: 3px; }

  .nav-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2);
    margin-top: var(--space-3);
    padding-top: var(--space-3);
    border-top: var(--border-thin) dotted var(--color-contrast-line);
    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);
  }

  .nav-meta-label { color: var(--color-contrast-accent); }

  .nav-toggle {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 95;
    display: flex;
    align-items: center;
    gap: var(--space-2);
    height: 56px;
    padding-inline: var(--space-4);
    background: var(--color-contrast-surface);
    color: var(--color-contrast-ink);
    border-top: var(--border-thin) solid var(--color-contrast-line);
    font-size: var(--text-sm);
    text-align: left;
  }

  .nav-toggle-bars { display: grid; gap: 3px; width: 18px; }

  .nav-toggle-bars i {
    display: block;
    height: var(--border-thin);
    background: currentColor;
    transition: transform 0.2s ease, opacity 0.2s ease;
  }

  .nav-toggle-label {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    letter-spacing: 0.1em;
    color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
  }

  .nav-toggle-index {
    margin-left: auto;
    padding: 2px 8px;
    border: var(--border-thin) solid var(--color-contrast-line);
    border-radius: var(--radius-sm);
    font-family: var(--font-mono);
    font-size: var(--text-sm);
    color: var(--color-contrast-accent);
  }

  .nav-toggle-version {
    font-family: var(--font-mono);
    font-size: var(--text-xs);
    color: var(--color-contrast-accent);
  }

  .site-header[data-open="true"] .nav-toggle-bars i:nth-child(1) { transform: translateY(4px) rotate(45deg); }
  .site-header[data-open="true"] .nav-toggle-bars i:nth-child(2) { opacity: 0; }
  .site-header[data-open="true"] .nav-toggle-bars i:nth-child(3) { transform: translateY(-4px) rotate(-45deg); }

  .side-index { position: static; }
}

@media (max-width: 680px) {
  .shell { padding-inline: var(--space-3); }

  .grid {
    grid-template-columns: repeat(6, minmax(0, 1fr));
    gap: var(--space-3);
  }

  .span-2,
  .span-3,
  .span-4,
  .span-5,
  .span-6,
  .span-7,
  .span-8,
  .span-9,
  .span-10,
  .span-12 { grid-column: span 6; }

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

  .sec-title { font-size: var(--text-2xl); }

  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: var(--space-4); }
  .footer-col { padding-left: var(--space-2); }
  .footer-bottom { justify-content: flex-start; }
}

/* ---------- 14. 无障碍与动效偏好 ---------- */
@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; }
}