:root {
  --color-surface: #ffffff;
  --color-surface-alt: #f6f6f6;
  --color-surface-deep: #e9eaea;
  --color-ink: #474c52;
  --color-ink-soft: #6c737a;
  --color-ink-muted: #797f86;
  --color-line: #dedfe0;
  --color-primary: #3e79b7;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4ecf5;
  --color-accent: #0f857a;
  --color-accent-ink: #ffffff;
  --color-highlight: #d4e9e7;
  --color-focus: #078378;
  --color-contrast-surface: #0e1216;
  --color-contrast-ink: #e4e5e7;
  --color-contrast-line: #3d4044;
  --color-contrast-accent: #1ae5d3;
  --overlay-scrim: linear-gradient(180deg, rgba(14, 18, 22, 0.35) 0%, rgba(14, 18, 22, 0.72) 55%, rgba(14, 18, 22, 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: 10.7px;
  --text-sm: 13.4px;
  --text-base: 15px;
  --text-lg: 18.8px;
  --text-xl: 23.4px;
  --text-2xl: 29.3px;
  --text-3xl: 36.6px;
  --text-4xl: 45.8px;
  --text-display: clamp(39px, 8.0vw, 103px);
  --text-figure: clamp(33px, 5.8vw, 74px);
  --weight-heading: 649;
  --weight-body: 400;
  --leading-body: 1.75;
  --leading-heading: 1.3;
  --tracking-heading: 0.003em;
  --radius-sm: 14px;
  --radius-md: 15px;
  --radius-lg: 16px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 6px 18px rgba(71, 76, 82, 0.08);
  --shadow-2: 0 18px 44px rgba(71, 76, 82, 0.14);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1320px;
  --measure: 66ch;
  --gutter: 24px;
  --section-y: 69px;
  --section-y-lg: 97px;
}

/* ============================================================
   1. 重置与中文排版基线
   ============================================================ */
*,
*::before,
*::after { box-sizing: border-box; }

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

body {
  margin: 0;
  padding-top: 112px;
  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);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

main { display: block; }

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

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);
  color: var(--color-ink);
  text-wrap: balance;
}

p {
  margin: 0 0 var(--space-2);
  text-wrap: pretty;
}

ul, ol { margin: 0; padding: 0; }

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s ease, border-color 0.2s ease, background-color 0.2s ease;
}

a:hover { text-decoration: underline; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
  border-radius: 4px;
}

[hidden] { display: none !important; }

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

.mono {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.02em;
}

/* ============================================================
   2. 布局骨架
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding-inline: var(--gutter);
}

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--tight { padding-block: var(--space-6); }

.rule-thick { border-top: calc(var(--border-thick) * 3) solid var(--color-line); }
.rule-double { border-top: calc(var(--border-thick) * 3) double var(--color-line); }

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: var(--space-3);
}

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

.stack { display: flex; flex-direction: column; gap: var(--space-3); }
.stack--tight { gap: var(--space-2); }

[id] { scroll-margin-top: 128px; }

/* ============================================================
   3. 文字角色
   ============================================================ */
.display {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.02;
  letter-spacing: -0.03em;
  color: var(--color-ink);
}

.figure {
  font-family: var(--font-heading);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--color-ink);
}

.title-page {
  font-size: var(--text-3xl);
  line-height: 1.15;
  margin-bottom: var(--space-2);
}

.title-block {
  font-size: var(--text-2xl);
  line-height: 1.2;
}

.title-entry {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.35;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.eyebrow::before {
  content: "";
  width: 18px;
  height: calc(var(--border-thick) * 3);
  background: var(--color-primary);
  flex: 0 0 auto;
}

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

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

.prose h2 {
  font-size: var(--text-2xl);
  margin: var(--space-6) 0 var(--space-2);
}

.prose h3 {
  font-size: var(--text-xl);
  margin: var(--space-4) 0 var(--space-2);
}

.prose p { margin: 0 0 var(--space-3); }

.prose ul,
.prose ol {
  margin: 0 0 var(--space-3);
  padding-left: 1.35em;
}

.prose li { margin-bottom: var(--space-1); }

.prose blockquote {
  margin: var(--space-4) 0;
  padding: var(--space-2) var(--space-3);
  border-left: calc(var(--border-thick) * 3) solid var(--color-accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--color-primary-soft);
  color: var(--color-ink-soft);
}

/* ============================================================
   4. 跳转链接
   ============================================================ */
.skip-link {
  position: absolute;
  top: var(--space-2);
  left: -9999px;
  z-index: 300;
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-pill);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  box-shadow: var(--shadow-2);
}

.skip-link:focus {
  left: var(--space-3);
  text-decoration: none;
}

/* ============================================================
   5. 悬浮胶囊头部
   ============================================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 120;
  padding: var(--space-3) 0;
  transition: padding 0.3s ease;
}

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

.nav-shell {
  position: relative;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  min-height: 64px;
  padding: var(--space-1) var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background: color-mix(in srgb, var(--color-surface) 88%, var(--color-primary-soft));
  box-shadow: var(--shadow-1);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  transition: min-height 0.3s ease, box-shadow 0.3s ease, background-color 0.3s ease;
}

.site-header[data-compact="true"] { padding: var(--space-2) 0; }
.site-header[data-compact="true"] .nav-shell {
  min-height: 54px;
  box-shadow: var(--shadow-2);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding-left: var(--space-1);
  flex: 0 0 auto;
  text-decoration: none;
}

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

.brand__mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: -0.03em;
}

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

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  line-height: 1.15;
  color: var(--color-ink);
}

.brand__tagline {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  line-height: 1.2;
  color: var(--color-ink-muted);
}

/* 导航 */
.nav { margin-left: auto; }

.nav__list {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  list-style: none;
}

.nav__link {
  display: inline-flex;
  align-items: center;
  height: 36px;
  padding: 0 var(--space-2);
  border-radius: var(--radius-pill);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  white-space: nowrap;
}

.nav__link:hover {
  background: var(--color-primary-soft);
  color: var(--color-primary);
  text-decoration: none;
}

.nav__link[aria-current="page"] {
  background: var(--color-accent);
  color: var(--color-accent-ink);
  font-weight: 600;
}

.nav__link[aria-current="page"]:hover {
  background: color-mix(in srgb, var(--color-accent) 86%, var(--color-contrast-surface));
  color: var(--color-accent-ink);
}

/* 胶囊右侧工具区 */
.header-utility {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin-left: var(--space-1);
  flex: 0 0 auto;
}

.version-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px var(--space-2);
  border-radius: var(--radius-pill);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1;
  white-space: nowrap;
  text-decoration: none;
}

.version-chip:hover { text-decoration: none; }

.version-chip__key {
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, var(--color-contrast-surface));
  letter-spacing: 0.06em;
}

.version-chip__value {
  color: var(--color-contrast-accent);
  font-weight: 700;
  letter-spacing: 0.04em;
}

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  padding: 0;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-surface);
  color: var(--color-ink);
  cursor: pointer;
}

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 16px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform 0.24s ease;
}

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

.site-header[data-open="true"] .nav-toggle {
  background: var(--color-contrast-surface);
  border-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.site-header[data-open="true"] .nav-toggle__bars { background: transparent; }
.site-header[data-open="true"] .nav-toggle__bars::before { transform: translateY(5px) rotate(45deg); }
.site-header[data-open="true"] .nav-toggle__bars::after { transform: translateY(-5px) rotate(-45deg); }

/* ============================================================
   6. 模块与 Bento 组件
   ============================================================ */
.module {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  box-shadow: var(--shadow-1);
  transition: transform 0.28s ease, box-shadow 0.28s ease;
}

.module:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-2);
}

.module--alt { background: var(--color-surface-alt); }
.module--deep { background: var(--color-surface-deep); border-color: transparent; }

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

.module--focus .module__title,
.module--focus .figure,
.module--focus .display { color: var(--color-accent-ink); }

.module--focus .module__text,
.module--focus .eyebrow { color: color-mix(in srgb, var(--color-accent-ink) 82%, var(--color-accent)); }

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

.module--contrast .module__title,
.module--contrast .figure,
.module--contrast h2,
.module--contrast h3 { color: var(--color-contrast-ink); }

.module--contrast .module__text,
.module--contrast .eyebrow { color: color-mix(in srgb, var(--color-contrast-ink) 72%, var(--color-contrast-surface)); }

.module--contrast .eyebrow::before { background: var(--color-contrast-accent); }

.module__title {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--weight-heading);
  line-height: 1.25;
  color: var(--color-ink);
}

.module__text {
  margin: 0;
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.module__foot {
  margin-top: auto;
  padding-top: var(--space-2);
  border-top: var(--border-thin) solid var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.module--contrast .module__foot { border-top-color: var(--color-contrast-line); }

/* ============================================================
   7. 标签、条目、索引
   ============================================================ */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.5;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

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

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

.module--contrast .tag,
.site-footer .tag {
  background: color-mix(in srgb, var(--color-contrast-accent) 16%, transparent);
  color: var(--color-contrast-accent);
}

.entry {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding: var(--space-3) 0;
  border-bottom: var(--border-thin) solid var(--color-line);
}

.entry__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.entry__meta span { white-space: nowrap; }

.entry__title {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.35;
}

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

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  margin: 0 0 var(--space-3);
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

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

.breadcrumb li:not(:last-child)::after {
  content: "/";
  margin: 0 var(--space-1);
  color: var(--color-line);
}

.breadcrumb a { color: var(--color-ink-soft); }
.breadcrumb [aria-current="page"] { color: var(--color-ink); }

/* 侧边章节目录 */
.toc {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  background: var(--color-surface-alt);
}

.toc__title {
  margin: 0 0 var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-ink-muted);
}

.toc__link {
  display: block;
  padding: 6px var(--space-2);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  border-left: calc(var(--border-thick) * 3) solid transparent;
}

.toc__link:hover {
  background: var(--color-primary-soft);
  color: var(--color-primary);
  text-decoration: none;
}

.toc__link.is-active {
  background: var(--color-primary-soft);
  border-left-color: var(--color-accent);
  color: var(--color-primary);
  font-weight: 600;
}

/* 折叠块 */
.collapse {
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  overflow: hidden;
}

.collapse + .collapse { margin-top: var(--space-2); }

.collapse__trigger {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  width: 100%;
  padding: var(--space-3);
  border: 0;
  background: transparent;
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  text-align: left;
  cursor: pointer;
}

.collapse__trigger:hover { background: var(--color-surface-alt); }

.collapse__mark {
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  display: grid;
  place-items: center;
  border-radius: var(--radius-pill);
  background: var(--color-primary-soft);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1;
}

.collapse__panel {
  display: none;
  padding: 0 var(--space-3) var(--space-3);
  border-top: var(--border-thin) solid var(--color-line);
  padding-top: var(--space-3);
}

.collapse.is-open .collapse__panel { display: block; }
.collapse.is-open .collapse__mark { background: var(--color-accent); color: var(--color-accent-ink); }

/* ============================================================
   8. 按钮
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 11px var(--space-3);
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-pill);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  line-height: 1.2;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.22s ease, color 0.22s ease, border-color 0.22s ease, transform 0.22s ease;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-2px);
}

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

.btn--primary:hover {
  background: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface));
  color: var(--color-primary-ink);
}

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

.btn--accent:hover {
  background: color-mix(in srgb, var(--color-accent) 84%, var(--color-contrast-surface));
  color: var(--color-accent-ink);
}

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

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

.btn-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  align-items: center;
}

/* ============================================================
   9. 图片容器（页面阶段放置 <img> 占位）
   ============================================================ */
.media {
  position: relative;
  display: block;
  width: 100%;
  overflow: hidden;
  border-radius: var(--radius-lg);
  background: var(--color-surface-deep);
  aspect-ratio: 16 / 10;
}

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

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

.media--tint img {
  filter: grayscale(1) contrast(1.06);
}

.media--tint::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  background: var(--color-primary);
  mix-blend-mode: color;
  opacity: 0.62;
  pointer-events: none;
}

.media--tint.media--accent::before { background: var(--color-accent); }

.media--scrim::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 2;
  background: var(--overlay-scrim);
  pointer-events: none;
}

.media__label {
  position: absolute;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 3;
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-contrast-ink);
}

.media__caption {
  margin-top: var(--space-1);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

/* ============================================================
   10. 滚动显现与返回顶部
   ============================================================ */
.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.42s ease, transform 0.42s ease;
}

.has-js [data-reveal].is-revealed {
  opacity: 1;
  transform: translateY(0);
}

.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 110;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px var(--space-2);
  border: 0;
  border-radius: var(--radius-pill);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  box-shadow: var(--shadow-2);
  transition: opacity 0.28s ease, transform 0.28s ease, visibility 0.28s ease;
}

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

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

/* ============================================================
   11. 卡片式页脚
   ============================================================ */
.site-footer {
  margin-top: var(--section-y-lg);
  padding: var(--section-y) 0 var(--space-6);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: calc(var(--border-thick) * 3) solid var(--color-contrast-line);
}

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

.footer-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1.25fr 1fr;
  gap: var(--space-3);
}

.footer-panel {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-lg);
  background: color-mix(in srgb, var(--color-contrast-ink) 6%, var(--color-contrast-surface));
}

.footer-panel--focus {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}

.footer-panel__kicker {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-contrast-accent);
}

.footer-panel--focus .footer-panel__kicker {
  color: color-mix(in srgb, var(--color-accent-ink) 80%, var(--color-accent));
}

.footer-panel__title {
  margin: 0;
  font-size: var(--text-lg);
  line-height: 1.3;
  color: var(--color-contrast-ink);
}

.footer-panel--focus .footer-panel__title { color: var(--color-accent-ink); }

.footer-panel__text {
  margin: 0;
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, var(--color-contrast-surface));
}

.footer-panel--focus .footer-panel__text {
  color: color-mix(in srgb, var(--color-accent-ink) 86%, var(--color-accent));
}

.footer-panel__meta {
  margin: 0;
  font-size: var(--text-xs);
  line-height: 1.6;
  color: color-mix(in srgb, var(--color-contrast-ink) 64%, var(--color-contrast-surface));
}

.footer-panel--focus .footer-panel__meta {
  color: color-mix(in srgb, var(--color-accent-ink) 84%, var(--color-accent));
}

.footer-panel__value {
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--color-contrast-accent);
}

.footer-panel--focus .footer-panel__value {
  color: var(--color-accent-ink);
  background: color-mix(in srgb, var(--color-contrast-surface) 22%, var(--color-accent));
  padding: 1px 6px;
  border-radius: var(--radius-sm);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 6px;
  list-style: none;
}

.footer-links a {
  display: inline-block;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thin) solid transparent;
  padding-bottom: 1px;
}

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

.footer-contact {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  list-style: none;
}

.footer-contact li {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.footer-contact__key {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, var(--color-contrast-surface));
}

.footer-contact__val {
  font-size: var(--text-sm);
  line-height: 1.5;
  color: var(--color-contrast-ink);
  word-break: break-word;
}

.footer-baseline {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
  margin-top: var(--space-6);
  padding-top: var(--space-3);
  border-top: calc(var(--border-thick) * 3) double var(--color-contrast-line);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 66%, var(--color-contrast-surface));
}

.footer-baseline p { margin: 0; }

.footer-baseline__meta {
  font-family: var(--font-mono);
  letter-spacing: 0.06em;
  color: var(--color-contrast-accent);
}

/* ============================================================
   12. 响应式
   ============================================================ */
@media (max-width: 1180px) {
  .footer-grid { grid-template-columns: 1.3fr 1fr 1.2fr; }
  .footer-panel:last-child { grid-column: span 3; }
}

@media (max-width: 1040px) {
  body { padding-top: 88px; }

  .site-header { padding: var(--space-2) 0; }

  .nav-shell {
    min-height: 56px;
    padding: 6px var(--space-2);
  }

  .brand__tagline { display: none; }

  .nav {
    position: absolute;
    top: calc(100% + var(--space-1));
    left: 0;
    right: 0;
    display: none;
    max-height: min(72vh, 460px);
    overflow-y: auto;
    margin-left: 0;
    padding: var(--space-2);
    border: var(--border-thin) solid var(--color-line);
    border-radius: var(--radius-lg);
    background: var(--color-surface);
    box-shadow: var(--shadow-2);
  }

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

  .nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
  }

  .nav__link {
    height: auto;
    padding: 12px var(--space-2);
    border-radius: var(--radius-sm);
    font-size: var(--text-base);
  }

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

  .header-utility { margin-left: auto; }

  .version-chip { padding: 6px 10px; }
  .version-chip__key { display: none; }

  .footer-grid { grid-template-columns: 1fr 1fr; }
  .footer-panel:last-child { grid-column: span 2; }
}

@media (max-width: 900px) {
  .col-3, .col-4, .col-5 { grid-column: span 6; }
  .col-7, .col-8 { grid-column: span 12; }
  .col-6 { grid-column: span 6; }
}

@media (max-width: 640px) {
  .grid { grid-template-columns: repeat(6, minmax(0, 1fr)); }

  .col-3, .col-4, .col-5,
  .col-6, .col-7, .col-8 { grid-column: span 6; }

  .col-12 { grid-column: span 6; }

  .footer-grid { grid-template-columns: 1fr; }
  .footer-panel:last-child { grid-column: span 1; }

  .to-top { right: var(--space-2); bottom: var(--space-2); }

  .display { letter-spacing: -0.02em; }
}

@media (max-width: 420px) {
  .brand__mark { width: 34px; height: 34px; }
  .brand__name { font-size: var(--text-sm); }
}

/* ============================================================
   13. 动效降级
   ============================================================ */
@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;
  }

  .has-js [data-reveal] {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .module:hover,
  .btn:hover { transform: none; }
}