:root {
  --color-surface: #f0efee;
  --color-surface-alt: #e8e6e5;
  --color-surface-deep: #dcdad8;
  --color-ink: #46423a;
  --color-ink-soft: #6c665b;
  --color-ink-muted: #898376;
  --color-line: #d1d0ce;
  --color-primary: #897243;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e2ded6;
  --color-accent: #707807;
  --color-accent-ink: #ffffff;
  --color-highlight: #d9dac4;
  --color-focus: #676f01;
  --color-contrast-surface: #211e19;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #4d4a46;
  --color-contrast-accent: #dff10e;
  --overlay-scrim: linear-gradient(180deg, rgba(33, 30, 25, 0.35) 0%, rgba(33, 30, 25, 0.72) 55%, rgba(33, 30, 25, 0.92) 100%);
  --font-heading: "Songti SC", "Source Han Serif SC", "Noto Serif SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 12.9px;
  --text-sm: 15.5px;
  --text-base: 17px;
  --text-lg: 20.4px;
  --text-xl: 24.5px;
  --text-2xl: 29.4px;
  --text-3xl: 35.3px;
  --text-4xl: 42.3px;
  --text-display: clamp(35px, 7.2vw, 92px);
  --text-figure: clamp(29px, 5.2vw, 66px);
  --weight-heading: 671;
  --weight-body: 400;
  --leading-body: 1.84;
  --leading-heading: 1.23;
  --tracking-heading: 0.008em;
  --radius-sm: 3px;
  --radius-md: 4px;
  --radius-lg: 5px;
  --radius-pill: 5px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 1px 0 rgba(70, 66, 58, 0.12);
  --shadow-2: 0 2px 0 rgba(70, 66, 58, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1200px;
  --measure: 67ch;
  --gutter: 16px;
  --section-y: 73px;
  --section-y-lg: 102px;
}

/* ===== 01. Reset ===== */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body, h1, h2, h3, h4, h5, h6, p, ul, ol, li, figure, figcaption, blockquote, dl, dt, dd { margin: 0; padding: 0; }
ul, ol { list-style: none; }
img, svg, video { display: block; max-width: 100%; }
img { height: auto; }
button { font: inherit; color: inherit; background: none; border: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }
main { display: block; }
strong, b { font-weight: var(--weight-heading); }

/* ===== 02. 基础排版 ===== */
body {
  min-height: 100vh;
  position: relative;
  isolation: isolate;
  overflow-x: hidden;
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  font-weight: var(--weight-body);
}
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background-image:
    radial-gradient(58% 44% at 10% 2%, color-mix(in srgb, var(--color-primary) 9%, transparent), transparent 72%),
    radial-gradient(52% 42% at 94% 84%, color-mix(in srgb, var(--color-accent) 8%, transparent), transparent 74%);
}
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);
  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); }
small { font-size: var(--text-xs); }
.mono, .num { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
.eyebrow {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}
.kicker {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-primary);
}
.kicker::before {
  content: "";
  width: 22px;
  height: 2px;
  background-color: var(--color-primary);
}
.hl {
  background-color: var(--color-highlight);
  padding: 0.06em 0.24em;
  border-radius: var(--radius-sm);
  box-decoration-break: clone;
  -webkit-box-decoration-break: clone;
}
.ul-accent {
  border-bottom: 2px solid var(--color-accent);
  padding-bottom: 1px;
}
.measure { max-width: var(--measure); }
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
}

/* ===== 03. 布局工具 ===== */
.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); }
.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)); }
.split-3-9 { display: grid; grid-template-columns: 3fr 9fr; gap: var(--space-6); }
.split-4-8 { display: grid; grid-template-columns: 4fr 8fr; gap: var(--space-6); }
.split-5-7 { display: grid; grid-template-columns: 5fr 7fr; gap: var(--space-6); }
.section-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-2) var(--space-3);
  margin-bottom: var(--space-4);
}
.section-head h2 { font-size: var(--text-2xl); }
.section-head p { font-size: var(--text-sm); color: var(--color-ink-soft); max-width: 52ch; }

/* ===== 04. 焦点与跳过链接 ===== */
:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}
.skip-link {
  position: absolute;
  left: var(--space-3);
  top: -120px;
  z-index: 200;
  display: inline-block;
  padding: 11px 20px;
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-2);
  font-size: var(--text-sm);
  transition: top 0.16s ease;
}
.skip-link:focus { top: var(--space-3); }

/* ===== 05. 页头 ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background-color: var(--color-surface);
  box-shadow: var(--shadow-1);
}
.site-header::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 3px;
  pointer-events: none;
  background-image: repeating-linear-gradient(90deg, var(--color-line) 0 1px, transparent 1px 13px);
  opacity: 0.7;
}
.header-frame {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: var(--space-3);
  padding-block: 14px;
}
.scroll-progress {
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-accent);
  z-index: 2;
}
.brand-lockup {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}
.brand-mark {
  display: grid;
  place-items: center;
  min-width: 44px;
  height: 40px;
  padding: 0 9px;
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-base);
  font-weight: 700;
  letter-spacing: 0.04em;
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-2);
  transform: rotate(-1.5deg);
  transition: box-shadow 0.16s ease;
}
.brand-lockup:hover .brand-mark { box-shadow: 0 3px 0 color-mix(in srgb, var(--color-ink) 26%, transparent); }
.brand-text { display: block; min-width: 0; }
.brand-name {
  display: block;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.15;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}
.brand-sign {
  display: block;
  margin-top: 2px;
  font-size: var(--text-xs);
  letter-spacing: 0.05em;
  color: var(--color-ink-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.primary-nav { justify-self: center; min-width: 0; }
.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
  padding: 4px;
  background-color: var(--color-surface-alt);
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-1);
}
.nav-list a {
  position: relative;
  display: block;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  white-space: nowrap;
  transition: background-color 0.16s ease, color 0.16s ease, box-shadow 0.16s ease;
}
.nav-list a:hover {
  background-color: var(--color-surface);
  color: var(--color-ink);
  box-shadow: var(--shadow-1);
}
.nav-list a[aria-current="page"] {
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  box-shadow: var(--shadow-2);
}
.nav-list a[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -6px;
  width: 12px;
  height: 3px;
  transform: translateX(-50%);
  background-color: var(--color-accent);
  border-radius: 1px;
}
.header-status {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  justify-self: end;
  min-width: 0;
}
.status-chip {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 7px 11px;
  font-size: var(--text-xs);
  line-height: 1.2;
  color: var(--color-ink-soft);
  background-color: var(--color-surface-deep);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-1);
  white-space: nowrap;
}
.status-chip--mono {
  font-family: var(--font-mono);
  letter-spacing: 0.05em;
  color: var(--color-accent);
}
.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background-color: var(--color-accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-accent) 20%, transparent);
  animation: status-breathe 2.8s ease-in-out infinite;
}
@keyframes status-breathe {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}
.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  justify-self: end;
  padding: 9px 13px;
  background-color: var(--color-surface-alt);
  color: var(--color-ink);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
}
.nav-toggle-icon { display: grid; gap: 3px; width: 16px; }
.nav-toggle-icon span {
  display: block;
  height: 1.5px;
  background-color: currentColor;
  transition: transform 0.16s ease, opacity 0.16s ease;
}
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(1) { transform: translateY(4.5px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-icon span:nth-child(3) { transform: translateY(-4.5px) rotate(-45deg); }

/* ===== 06. 页脚 ===== */
.site-footer {
  position: relative;
  margin-top: var(--section-y-lg);
  padding-block: var(--section-y-lg) var(--space-4);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  overflow: hidden;
}
.site-footer::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 8px;
  background-image: repeating-linear-gradient(90deg, var(--color-contrast-line) 0 1px, transparent 1px 14px);
  opacity: 0.9;
}
.footer-frame { position: relative; z-index: 1; }
.footer-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr 1.6fr;
  gap: var(--space-6);
}
.footer-col-title {
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 400;
  letter-spacing: 0.18em;
  color: var(--color-contrast-accent);
}
.footer-links li + li { margin-top: 10px; }
.footer-links a {
  display: inline-block;
  font-size: var(--text-sm);
  color: color-mix(in srgb, var(--color-contrast-ink) 82%, transparent);
  border-bottom: 1px solid transparent;
  transition: color 0.16s ease, border-color 0.16s ease;
}
.footer-links a:hover {
  color: var(--color-contrast-accent);
  border-bottom-color: var(--color-contrast-accent);
}
.footer-contact li {
  margin-bottom: var(--space-2);
  font-size: var(--text-sm);
  line-height: 1.7;
  color: color-mix(in srgb, var(--color-contrast-ink) 86%, transparent);
}
.footer-label {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: color-mix(in srgb, var(--color-contrast-ink) 58%, transparent);
}
.footer-link { color: var(--color-contrast-accent); }
.copy-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 6px;
  padding: 5px 10px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-contrast-ink);
  background-color: color-mix(in srgb, var(--color-contrast-ink) 10%, transparent);
  border-radius: var(--radius-sm);
  box-shadow: inset 0 0 0 1px var(--color-contrast-line);
  transition: background-color 0.16s ease, color 0.16s ease;
}
.copy-btn:hover {
  background-color: color-mix(in srgb, var(--color-contrast-accent) 20%, transparent);
  color: var(--color-contrast-accent);
}
.copy-btn[data-copied="true"] {
  background-color: color-mix(in srgb, var(--color-contrast-accent) 26%, transparent);
  color: var(--color-contrast-accent);
}
.footer-region {
  margin-top: var(--space-6);
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-contrast-line);
  font-size: var(--text-xs);
  line-height: 1.8;
  color: color-mix(in srgb, var(--color-contrast-ink) 62%, transparent);
  max-width: 74ch;
}
.footer-mark {
  margin-top: var(--space-3);
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: clamp(calc(var(--text-4xl) * 1.35), 14vw, calc(var(--text-4xl) * 3.5));
  line-height: 0.86;
  letter-spacing: -0.02em;
  white-space: nowrap;
  color: color-mix(in srgb, var(--color-contrast-ink) 16%, transparent);
  user-select: none;
}
@supports (-webkit-text-stroke: 1px red) {
  .footer-mark {
    color: transparent;
    -webkit-text-stroke: 1px color-mix(in srgb, var(--color-contrast-ink) 42%, transparent);
  }
}
.footer-base {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-2);
  margin-top: var(--space-4);
  padding-top: var(--space-3);
  border-top: 1px solid 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) 68%, transparent);
}

/* ===== 07. 按钮 ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 12px 22px;
  font-size: var(--text-sm);
  font-family: var(--font-body);
  color: var(--color-ink);
  background-color: var(--color-surface-alt);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-2);
  transition: transform 0.16s ease, box-shadow 0.16s ease, background-color 0.16s ease, color 0.16s ease;
}
.btn:hover {
  transform: translateY(-1px);
  box-shadow: 0 3px 0 color-mix(in srgb, var(--color-ink) 24%, transparent);
}
.btn:active { transform: translateY(0); box-shadow: var(--shadow-1); }
.btn--primary { background-color: var(--color-primary); color: var(--color-primary-ink); }
.btn--accent { background-color: var(--color-accent); color: var(--color-accent-ink); }
.btn--ghost {
  background-color: transparent;
  color: var(--color-primary);
  box-shadow: inset 0 0 0 var(--border-thin) var(--color-primary);
}
.btn--ghost:hover { box-shadow: inset 0 0 0 var(--border-thin) var(--color-primary), 0 3px 0 color-mix(in srgb, var(--color-primary) 26%, transparent); }

/* ===== 08. 标签与贴纸 ===== */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  line-height: 1.5;
  color: var(--color-ink-soft);
  background-color: var(--color-surface-deep);
  border-radius: var(--radius-sm);
}
.tag--primary { background-color: var(--color-primary-soft); color: var(--color-primary); }
.tag--accent { background-color: var(--color-accent); color: var(--color-accent-ink); }
.tag--outline {
  background-color: transparent;
  color: var(--color-primary);
  box-shadow: inset 0 0 0 var(--border-thin) var(--color-primary);
}
.sticker {
  position: absolute;
  top: -12px;
  left: 18px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-primary);
  background-color: var(--color-primary-soft);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-2);
  transform: rotate(-1deg);
}
.sticker--accent {
  color: var(--color-accent-ink);
  background-color: var(--color-accent);
}
.sticker--corner {
  top: auto;
  left: auto;
  right: 18px;
  bottom: -12px;
  transform: rotate(1.2deg);
}

/* ===== 09. 纸张面板 ===== */
.paper {
  position: relative;
  padding: var(--space-3) var(--space-3) calc(var(--space-3) + 4px);
  background-color: var(--color-surface-alt);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-2);
}
.paper--raised { background-color: var(--color-surface); }
.paper--deep { background-color: var(--color-surface-deep); }
.paper--offset { transform: translate(-6px, -6px); }
.paper--offset-alt { transform: translate(6px, 6px); }
.paper--dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}
.paper--dark h2, .paper--dark h3, .paper--dark h4 { color: var(--color-contrast-ink); }
.paper--dark p, .paper--dark li { color: color-mix(in srgb, var(--color-contrast-ink) 84%, transparent); }
.paper--dark .sticker { color: var(--color-contrast-ink); background-color: color-mix(in srgb, var(--color-contrast-ink) 12%, transparent); box-shadow: none; }
.paper--dark .sticker--accent { color: var(--color-contrast-surface); background-color: var(--color-contrast-accent); }

/* ===== 10. 图片容器 ===== */
.media {
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-md);
  background-color: var(--color-surface-deep);
  box-shadow: var(--shadow-2);
  aspect-ratio: 16 / 9;
}
.media > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: saturate(0.55) contrast(1.04) sepia(0.12);
}
.media::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  background: var(--overlay-scrim);
  opacity: 0;
  transition: opacity 0.2s ease;
}
.media[data-overlay="true"]::after { opacity: 1; }
.media-caption {
  position: absolute;
  z-index: 2;
  left: var(--space-3);
  right: var(--space-3);
  bottom: var(--space-3);
  font-size: var(--text-xs);
  line-height: 1.7;
  color: var(--color-contrast-ink);
}
.media--wide { aspect-ratio: 21 / 9; }
.media--square { aspect-ratio: 1 / 1; }
.media--portrait { aspect-ratio: 3 / 4; }

/* ===== 11. 正文 / 面包屑 / 表格 ===== */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  padding-block: var(--space-3);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
}
.breadcrumb li { display: flex; align-items: center; gap: var(--space-1); }
.breadcrumb li + li::before { content: "/"; color: var(--color-line); }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb [aria-current="page"] { color: var(--color-ink-soft); }
.prose {
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}
.prose > * + * { margin-top: var(--space-3); }
.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 { padding-left: 1.4em; }
.prose ul { list-style: square; }
.prose ol { list-style: decimal; }
.prose li + li { margin-top: 6px; }
.prose ul li::marker { color: var(--color-primary); }
.prose blockquote {
  padding: var(--space-3);
  background-color: var(--color-highlight);
  border-radius: var(--radius-md);
  color: var(--color-ink);
  font-size: var(--text-sm);
}
.prose code {
  font-family: var(--font-mono);
  font-size: 0.92em;
  padding: 0.1em 0.36em;
  background-color: var(--color-surface-deep);
  border-radius: var(--radius-sm);
}
.data-table {
  width: 100%;
  font-size: var(--text-sm);
}
.data-table caption {
  padding-bottom: var(--space-2);
  text-align: left;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}
.data-table th, .data-table td {
  padding: 12px 14px;
  text-align: left;
  vertical-align: top;
  border-bottom: var(--border-thin) solid var(--color-line);
}
.data-table thead th {
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  border-bottom: var(--border-thin) solid var(--color-ink-muted);
}
.data-table tbody tr:nth-child(even) { background-color: var(--color-surface-deep); }
.data-table td.num { font-family: var(--font-mono); font-variant-numeric: tabular-nums; }
.data-table th[scope="row"] { font-weight: var(--weight-heading); color: var(--color-ink); }
.link-list li + li { margin-top: 10px; }

/* ===== 12. 章节目录 / 返回顶部 / 显现 ===== */
.toc-nav {
  position: sticky;
  top: calc(var(--space-8) + 24px);
  align-self: start;
}
.toc-title {
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}
.toc-link {
  display: block;
  padding: 7px 0 7px 14px;
  font-size: var(--text-sm);
  line-height: 1.6;
  color: var(--color-ink-muted);
  border-left: 2px solid var(--color-line);
  transition: color 0.16s ease, border-color 0.16s ease, background-color 0.16s ease;
}
.toc-link:hover { color: var(--color-ink); }
.toc-link[aria-current="true"] {
  color: var(--color-primary);
  border-left-color: var(--color-primary);
  background: linear-gradient(90deg, var(--color-primary-soft), transparent);
}
.to-top {
  position: fixed;
  right: var(--space-4);
  bottom: var(--space-4);
  z-index: 70;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-contrast-ink);
  background-color: var(--color-contrast-surface);
  border-radius: var(--radius-pill);
  box-shadow: var(--shadow-2);
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
}
.to-top[data-visible="true"] {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.to-top:hover { color: var(--color-contrast-accent); }
.js [data-reveal] {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease;
}
.js [data-reveal][data-visible="true"] {
  opacity: 1;
  transform: none;
}

/* ===== 13. 响应式 ===== */
@media (max-width: 1080px) {
  .nav-list a { padding: 8px 11px; font-size: var(--text-xs); }
  .brand-sign { display: none; }
}
@media (max-width: 900px) {
  .header-frame {
    grid-template-columns: minmax(0, 1fr) auto;
    row-gap: var(--space-2);
    padding-block: 12px;
  }
  .nav-toggle { display: inline-flex; }
  .primary-nav {
    grid-column: 1 / -1;
    justify-self: stretch;
    display: none;
  }
  .primary-nav[data-open="true"] { display: block; }
  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 3px;
    padding: 8px;
    border-radius: var(--radius-lg);
  }
  .nav-list a { padding: 11px 14px; font-size: var(--text-sm); }
  .nav-list a[aria-current="page"]::after {
    left: 14px;
    top: 50%;
    bottom: auto;
    transform: translateY(-50%);
    width: 3px;
    height: 14px;
  }
  .header-status {
    grid-column: 1 / -1;
    justify-self: start;
    flex-wrap: wrap;
  }
  .split-3-9, .split-4-8, .split-5-7 { grid-template-columns: minmax(0, 1fr); gap: var(--space-4); }
  .grid--3, .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .toc-nav { position: static; }
}
@media (max-width: 640px) {
  .container { padding-inline: var(--space-2); }
  .header-status { display: none; }
  .brand-name { font-size: var(--text-base); }
  .brand-mark { min-width: 38px; height: 34px; font-size: var(--text-sm); }
  .grid--2, .grid--3, .grid--4 { grid-template-columns: minmax(0, 1fr); }
  .footer-grid { grid-template-columns: minmax(0, 1fr); gap: var(--space-4); }
  .footer-base { flex-direction: column; }
  .to-top { right: var(--space-2); bottom: var(--space-2); }
  .data-table th, .data-table td { padding: 10px 10px; }
  .data-table { font-size: var(--text-xs); }
}

/* ===== 14. 动效克制 ===== */
@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 [data-reveal] { opacity: 1; transform: none; }
  .to-top { transform: none; }
}