:root {
  --color-surface: #fbfbfb;
  --color-surface-alt: #f2f2f3;
  --color-surface-deep: #e6e5e7;
  --color-ink: #4b4757;
  --color-ink-soft: #726d82;
  --color-ink-muted: #7a7689;
  --color-line: #dbdbdd;
  --color-primary: #5a3ac5;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e4e0f3;
  --color-accent: #c328d7;
  --color-accent-ink: #ffffff;
  --color-highlight: #f1d5f5;
  --color-focus: #c119d6;
  --color-contrast-surface: #110f19;
  --color-contrast-ink: #e5e4e7;
  --color-contrast-line: #403e46;
  --color-contrast-accent: #c839db;
  --overlay-scrim: linear-gradient(180deg, rgba(17, 15, 25, 0.35) 0%, rgba(17, 15, 25, 0.72) 55%, rgba(17, 15, 25, 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: 11.0px;
  --text-sm: 14.7px;
  --text-base: 17px;
  --text-lg: 22.7px;
  --text-xl: 30.2px;
  --text-2xl: 40.3px;
  --text-3xl: 53.7px;
  --text-4xl: 71.5px;
  --text-display: clamp(47px, 9.7vw, 124px);
  --text-figure: clamp(39px, 7.0vw, 89px);
  --weight-heading: 612;
  --weight-body: 400;
  --leading-body: 1.79;
  --leading-heading: 1.29;
  --tracking-heading: -0.009em;
  --radius-sm: 14px;
  --radius-md: 18px;
  --radius-lg: 22px;
  --radius-pill: 999px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 6px 18px rgba(75, 71, 87, 0.08);
  --shadow-2: 0 18px 44px rgba(75, 71, 87, 0.14);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1280px;
  --measure: 70ch;
  --gutter: 24px;
  --section-y: 99px;
  --section-y-lg: 139px;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 104px;
}

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

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

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

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

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

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

address { font-style: normal; }

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

/* ============================================================
   02 · 玻璃层叠底：彩色底 / 内容层分离
   ============================================================ */
body {
  position: relative;
  isolation: isolate;
  min-height: 100vh;
  overflow-x: hidden;
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  color: var(--color-ink);
  background-color: var(--color-surface);
  -webkit-font-smoothing: antialiased;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    radial-gradient(58% 42% at 8% 2%, color-mix(in srgb, var(--color-primary) 46%, transparent) 0%, transparent 72%),
    radial-gradient(46% 34% at 94% 14%, color-mix(in srgb, var(--color-accent) 34%, transparent) 0%, transparent 74%),
    radial-gradient(64% 40% at 52% 48%, color-mix(in srgb, var(--color-primary) 14%, transparent) 0%, transparent 70%),
    radial-gradient(72% 46% at 46% 104%, color-mix(in srgb, var(--color-accent) 22%, transparent) 0%, transparent 72%);
}

/* ============================================================
   03 · 中文排版
   ============================================================ */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  text-wrap: balance;
}

p { text-wrap: pretty; }

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

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

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.01em;
}

/* ============================================================
   04 · 焦点与无障碍
   ============================================================ */
:focus { outline: none; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

.visually-hidden {
  position: absolute !important;
  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;
}

.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -120px;
  z-index: 200;
  display: inline-flex;
  align-items: center;
  padding: 10px 18px;
  border-radius: var(--radius-pill);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  box-shadow: var(--shadow-2);
  transition: top 0.18s ease;
}

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

/* ============================================================
   05 · 布局骨架
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

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

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

.section--deep .lede { color: color-mix(in srgb, var(--color-contrast-ink) 72%, transparent); }

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

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid--split { grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); }
.grid--wide-left { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); }
.grid--auto { grid-template-columns: repeat(auto-fit, minmax(232px, 1fr)); }

.stack { display: grid; gap: var(--space-3); }
.stack--lg { display: grid; gap: var(--space-6); }

/* ============================================================
   06 · 玻璃面板
   ============================================================ */
.glass {
  position: relative;
  padding: var(--space-4);
  border: var(--border-thin) solid color-mix(in srgb, var(--color-primary-ink) 58%, var(--color-line));
  border-radius: var(--radius-lg);
  background: color-mix(in srgb, var(--color-surface) 72%, transparent);
  box-shadow: var(--shadow-1);
  -webkit-backdrop-filter: blur(16px) saturate(1.25);
  backdrop-filter: blur(16px) saturate(1.25);
  transition: border-color 0.18s ease, box-shadow 0.18s ease, background-color 0.18s ease;
}

.glass:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-2);
}

.glass--tight { padding: var(--space-3); }

.glass--deep {
  border-color: var(--color-contrast-line);
  background: color-mix(in srgb, var(--color-contrast-surface) 78%, transparent);
  color: var(--color-contrast-ink);
}

.glass--deep:hover { border-color: var(--color-contrast-accent); }

.glass__top {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

/* ============================================================
   07 · 编号 / 徽标 / 标题
   ============================================================ */
.idx {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.section--deep .idx { color: var(--color-contrast-accent); }

.chapnum {
  font-family: var(--font-mono);
  font-size: var(--text-3xl);
  line-height: 1;
  letter-spacing: -0.02em;
  color: color-mix(in srgb, var(--color-primary) 26%, transparent);
}

.section--deep .chapnum { color: color-mix(in srgb, var(--color-contrast-accent) 42%, transparent); }

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 11px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background: color-mix(in srgb, var(--color-surface-alt) 82%, transparent);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.6;
  white-space: nowrap;
}

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

.badge--accent {
  border-color: color-mix(in srgb, var(--color-accent) 32%, transparent);
  background: var(--color-highlight);
  color: color-mix(in srgb, var(--color-accent) 78%, var(--color-ink));
}

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

.tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
}

.section-title {
  font-size: var(--text-2xl);
  color: inherit;
}

.section-title--sm { font-size: var(--text-xl); }

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

.prose {
  max-width: var(--measure);
  display: grid;
  gap: var(--space-2);
}

.prose a {
  color: var(--color-primary);
  border-bottom: 1px solid color-mix(in srgb, var(--color-primary) 40%, transparent);
}

.prose a:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* ============================================================
   08 · 按钮
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 11px 22px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background: color-mix(in srgb, var(--color-surface) 76%, transparent);
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  line-height: 1.4;
  cursor: pointer;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}

.btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: color-mix(in srgb, var(--color-primary-soft) 70%, transparent);
}

.btn--primary {
  border-color: color-mix(in srgb, var(--color-primary-ink) 34%, transparent);
  background: var(--color-primary);
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-1);
}

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

.btn--accent {
  border-color: color-mix(in srgb, var(--color-accent-ink) 36%, transparent);
  background: var(--color-accent);
  color: var(--color-accent-ink);
  box-shadow: var(--shadow-1);
}

.btn--accent:hover {
  border-color: color-mix(in srgb, var(--color-accent-ink) 60%, transparent);
  background: color-mix(in srgb, var(--color-accent) 76%, var(--color-primary));
  color: var(--color-accent-ink);
}

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

.btn--ghost:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
  background: color-mix(in srgb, var(--color-contrast-ink) 8%, transparent);
}

.btn--sm { padding: 8px 15px; font-size: var(--text-sm); }
.btn--block { width: 100%; }

/* ============================================================
   09 · 面包屑
   ============================================================ */
.breadcrumbs { padding-block: var(--space-3) var(--space-1); }

.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.breadcrumbs__list li {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
}

.breadcrumbs__list li + li::before {
  content: "/";
  color: color-mix(in srgb, var(--color-primary) 60%, transparent);
}

.breadcrumbs__list a {
  color: var(--color-ink-soft);
  border-bottom: 1px solid transparent;
}

.breadcrumbs__list a:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.breadcrumbs__list [aria-current="page"] {
  color: var(--color-ink);
  font-weight: var(--weight-heading);
}

/* ============================================================
   10 · 图片容器（展签式）
   ============================================================ */
.figure {
  position: relative;
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--color-contrast-surface);
}

.figure__media {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--color-contrast-surface);
}

.figure__media:empty {
  background:
    linear-gradient(140deg,
      color-mix(in srgb, var(--color-contrast-surface) 88%, var(--color-primary)) 0%,
      color-mix(in srgb, var(--color-contrast-surface) 86%, var(--color-accent)) 100%);
}

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

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

.figure__tag {
  position: absolute;
  left: var(--space-2);
  bottom: var(--space-2);
  z-index: 2;
  padding: 4px 11px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-pill);
  background: color-mix(in srgb, var(--color-contrast-surface) 74%, transparent);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
}

.figure__caption {
  margin-top: var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink-muted);
}

.section--deep .figure__caption { color: color-mix(in srgb, var(--color-contrast-ink) 66%, transparent); }

.figure--portrait .figure__media { aspect-ratio: 4 / 5; }
.figure--square .figure__media { aspect-ratio: 1 / 1; }
.figure--wide .figure__media { aspect-ratio: 21 / 9; }

/* ============================================================
   11 · 命令栏头部
   ============================================================ */
.cmd-bar {
  position: sticky;
  top: 0;
  z-index: 80;
  color: var(--color-ink);
  background: color-mix(in srgb, var(--color-surface) 84%, transparent);
  border-bottom: var(--border-thin) solid var(--color-line);
  -webkit-backdrop-filter: blur(18px) saturate(1.3);
  backdrop-filter: blur(18px) saturate(1.3);
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.cmd-bar[data-scrolled="true"] {
  background: color-mix(in srgb, var(--color-contrast-surface) 92%, transparent);
  border-bottom-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}

.cmd-bar__inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-2) var(--space-3);
}

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

.brand__mark {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-sm);
  background: linear-gradient(140deg, var(--color-primary) 0%, var(--color-accent) 100%);
  color: var(--color-primary-ink);
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  box-shadow: var(--shadow-1);
}

.brand__text {
  display: flex;
  flex-direction: column;
  gap: 2px;
  line-height: 1.2;
}

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

.brand__state {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.cmd-bar[data-scrolled="true"] .brand__state {
  color: color-mix(in srgb, var(--color-contrast-ink) 68%, transparent);
}

.dot {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: var(--radius-pill);
  background: var(--color-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-accent) 22%, transparent);
}

/* 命令栏导航 */
.nav { margin-left: auto; }

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

.nav__item { display: block; }

.nav__label { display: inline; }

.nav__link {
  display: inline-flex;
  align-items: baseline;
  gap: 6px;
  padding: 8px 13px;
  border: var(--border-thin) solid transparent;
  border-radius: var(--radius-pill);
  color: color-mix(in srgb, var(--color-ink) 76%, transparent);
  font-size: var(--text-sm);
  white-space: nowrap;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease;
}

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

.nav__link:hover {
  color: var(--color-ink);
  border-color: var(--color-line);
  background: color-mix(in srgb, var(--color-surface-alt) 84%, transparent);
}

.nav__link[aria-current="page"] {
  color: var(--color-primary-ink);
  background: var(--color-primary);
  border-color: color-mix(in srgb, var(--color-primary-ink) 42%, transparent);
  box-shadow: var(--shadow-1);
}

.nav__link[aria-current="page"] .nav__idx {
  color: color-mix(in srgb, var(--color-primary-ink) 76%, transparent);
}

.cmd-bar[data-scrolled="true"] .nav__link {
  color: color-mix(in srgb, var(--color-contrast-ink) 74%, transparent);
}

.cmd-bar[data-scrolled="true"] .nav__idx {
  color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent);
}

.cmd-bar[data-scrolled="true"] .nav__link:hover {
  color: var(--color-contrast-ink);
  border-color: var(--color-contrast-line);
  background: color-mix(in srgb, var(--color-contrast-ink) 10%, transparent);
}

.cmd-bar[data-scrolled="true"] .nav__link[aria-current="page"] {
  color: var(--color-contrast-surface);
  background: var(--color-contrast-accent);
  border-color: color-mix(in srgb, var(--color-contrast-ink) 36%, transparent);
}

.cmd-bar[data-scrolled="true"] .nav__link[aria-current="page"] .nav__idx {
  color: color-mix(in srgb, var(--color-contrast-surface) 74%, transparent);
}

/* 右侧动作区 */
.cmd-bar__actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  margin-left: var(--space-2);
  flex: 0 0 auto;
}

.cmd-bar__hint {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  white-space: nowrap;
}

.cmd-bar[data-scrolled="true"] .cmd-bar__hint {
  color: color-mix(in srgb, var(--color-contrast-ink) 64%, transparent);
}

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 9px 14px;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  color: inherit;
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  cursor: pointer;
  transition: border-color 0.18s ease, color 0.18s ease, background-color 0.18s ease;
}

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

.cmd-bar[data-scrolled="true"] .nav-toggle {
  border-color: var(--color-contrast-line);
  color: var(--color-contrast-ink);
}

.cmd-bar[data-scrolled="true"] .nav-toggle:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

.nav-toggle__bars {
  display: grid;
  gap: 3px;
  width: 16px;
}

.nav-toggle__bars i {
  display: block;
  height: 1.5px;
  border-radius: 2px;
  background: currentColor;
  transition: transform 0.18s ease, opacity 0.18s ease;
}

.cmd-bar[data-open="true"] .nav-toggle__bars i:nth-child(1) { transform: translateY(4.5px) rotate(45deg); }
.cmd-bar[data-open="true"] .nav-toggle__bars i:nth-child(2) { opacity: 0; }
.cmd-bar[data-open="true"] .nav-toggle__bars i:nth-child(3) { transform: translateY(-4.5px) rotate(-45deg); }

.nav-toggle__text { display: inline; }

/* 阅读进度刻度 */
.cmd-bar__meter {
  position: relative;
  height: 2px;
  overflow: hidden;
  background: color-mix(in srgb, var(--color-line) 72%, transparent);
}

.cmd-bar__meter span {
  display: block;
  width: 0%;
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-accent) 100%);
}

.cmd-bar[data-scrolled="true"] .cmd-bar__meter { background: var(--color-contrast-line); }

/* ============================================================
   12 · 页脚（边框式 + 刻度尺）
   ============================================================ */
.site-foot {
  margin-top: var(--space-8);
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.site-foot__ruler {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--gutter);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-3) var(--space-3) 0;
}

.site-foot__ruler span {
  display: block;
  height: 12px;
  border-top: var(--border-thin) solid var(--color-contrast-line);
  border-left: var(--border-thin) solid var(--color-contrast-line);
}

.site-foot__ruler span:last-child {
  border-right: var(--border-thin) solid var(--color-contrast-line);
}

.site-foot__inner {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-6) var(--space-3) var(--space-4);
}

.site-foot__grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-4) var(--gutter);
}

.foot-col__title {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin-bottom: var(--space-2);
  padding-bottom: var(--space-1);
  border-bottom: var(--border-thin) solid var(--color-contrast-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
}

.foot-col__title::after {
  content: "";
  width: 6px;
  height: 6px;
  margin-left: auto;
  border-radius: var(--radius-pill);
  background: var(--color-contrast-accent);
}

.foot-list {
  display: grid;
  gap: 9px;
}

.foot-list a {
  display: inline-block;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent);
  border-bottom: 1px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

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

.foot-contact {
  display: grid;
  gap: 10px;
}

.foot-contact__row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1);
  font-size: var(--text-sm);
}

.foot-contact__key {
  min-width: 42px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: color-mix(in srgb, var(--color-contrast-ink) 56%, transparent);
}

.foot-contact__val {
  color: color-mix(in srgb, var(--color-contrast-ink) 88%, transparent);
  font-size: var(--text-sm);
  word-break: break-word;
}

.foot-contact__val--wide {
  max-width: 30ch;
  font-family: var(--font-body);
}

.foot-copy {
  padding: 3px 10px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-pill);
  color: color-mix(in srgb, var(--color-contrast-ink) 80%, transparent);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  cursor: pointer;
  transition: border-color 0.18s ease, color 0.18s ease, background-color 0.18s ease;
}

.foot-copy:hover {
  border-color: var(--color-contrast-accent);
  color: var(--color-contrast-accent);
}

.foot-copy[data-copied="true"] {
  border-color: transparent;
  background: var(--color-contrast-accent);
  color: var(--color-contrast-surface);
}

.site-foot__base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-3);
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding: var(--space-3) var(--space-3) var(--space-4);
  border-top: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-xs);
  color: color-mix(in srgb, var(--color-contrast-ink) 64%, transparent);
}

.site-foot__sig { font-family: var(--font-body); }

.site-foot__icp { letter-spacing: 0.04em; }

.site-foot__stage {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 4px 12px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-pill);
  color: var(--color-contrast-accent);
  font-family: var(--font-mono);
}

/* ============================================================
   13 · 返回顶部 / 显现
   ============================================================ */
.to-top {
  position: fixed;
  right: var(--space-3);
  bottom: var(--space-3);
  z-index: 70;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 46px;
  height: 46px;
  border: var(--border-thin) solid var(--color-contrast-line);
  border-radius: var(--radius-pill);
  background: color-mix(in srgb, var(--color-contrast-surface) 90%, transparent);
  color: var(--color-contrast-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  box-shadow: var(--shadow-2);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.18s ease, transform 0.18s ease, visibility 0.18s ease,
              border-color 0.18s ease, color 0.18s ease;
}

.to-top[data-visible="true"] {
  opacity: 1;
  visibility: visible;
  transform: none;
}

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

.reveal { opacity: 1; }

.js .reveal {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.42s ease, transform 0.42s ease;
}

.js .reveal[data-shown="true"] {
  opacity: 1;
  transform: none;
}

/* ============================================================
   14 · 响应式
   ============================================================ */
@media (max-width: 1080px) {
  .nav-toggle { display: inline-flex; }

  .cmd-bar__hint { display: none; }

  .nav {
    position: absolute;
    top: calc(100% + 10px);
    left: var(--space-2);
    right: var(--space-2);
    z-index: 90;
    display: none;
    max-height: min(72vh, 520px);
    margin-left: 0;
    padding: var(--space-2);
    overflow-y: auto;
    border: var(--border-thin) solid var(--color-contrast-line);
    border-radius: var(--radius-lg);
    background: color-mix(in srgb, var(--color-contrast-surface) 97%, transparent);
    box-shadow: var(--shadow-2);
    -webkit-backdrop-filter: blur(18px);
    backdrop-filter: blur(18px);
  }

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

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

  .nav__item { width: 100%; }

  .nav .nav__link,
  .cmd-bar[data-scrolled="true"] .nav .nav__link {
    justify-content: flex-start;
    padding: 12px 14px;
    border-radius: var(--radius-sm);
    color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent);
    font-size: var(--text-base);
  }

  .nav .nav__idx,
  .cmd-bar[data-scrolled="true"] .nav .nav__idx { color: var(--color-contrast-accent); }

  .nav .nav__link:hover,
  .cmd-bar[data-scrolled="true"] .nav .nav__link:hover {
    color: var(--color-contrast-ink);
    border-color: var(--color-contrast-line);
    background: color-mix(in srgb, var(--color-contrast-ink) 10%, transparent);
  }

  .nav .nav__link[aria-current="page"],
  .cmd-bar[data-scrolled="true"] .nav .nav__link[aria-current="page"] {
    color: var(--color-contrast-surface);
    background: var(--color-contrast-accent);
    border-color: color-mix(in srgb, var(--color-contrast-ink) 36%, transparent);
  }

  .nav .nav__link[aria-current="page"] .nav__idx,
  .cmd-bar[data-scrolled="true"] .nav .nav__link[aria-current="page"] .nav__idx {
    color: color-mix(in srgb, var(--color-contrast-surface) 74%, transparent);
  }
}

@media (max-width: 1023px) {
  .grid--3,
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }

  .grid--split,
  .grid--wide-left { grid-template-columns: minmax(0, 1fr); }

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

@media (max-width: 767px) {
  html { scroll-padding-top: 88px; }

  .section { padding-block: calc(var(--section-y) * 0.66); }
  .section--lg { padding-block: calc(var(--section-y-lg) * 0.62); }

  .glass { padding: var(--space-3); border-radius: var(--radius-md); }
  .glass--tight { padding: var(--space-2); }

  .cmd-bar__inner {
    gap: var(--space-2);
    padding: var(--space-2);
  }

  .site-foot__ruler { padding-inline: var(--space-2); }

  .site-foot__inner { padding: var(--space-4) var(--space-2) var(--space-3); }

  .site-foot__base {
    padding: var(--space-3) var(--space-2) var(--space-6);
    justify-content: flex-start;
  }

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

@media (max-width: 639px) {
  .grid--2,
  .grid--3,
  .grid--4 { grid-template-columns: minmax(0, 1fr); }

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

  .site-foot__ruler { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .site-foot__ruler span:nth-child(n + 3) { display: none; }

  .nav-toggle__text { display: none; }

  .brand__state { display: none; }

  .foot-contact__val--wide { max-width: none; }
}

/* ============================================================
   15 · 减弱动效
   ============================================================ */
@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;
  }

  .js .reveal,
  .js .reveal[data-shown="true"] {
    opacity: 1;
    transform: none;
  }
}