:root {
  --color-surface: #efeeee;
  --color-surface-alt: #e7e5e5;
  --color-surface-deep: #dbd9d9;
  --color-ink: #4c3d3f;
  --color-ink-soft: #766062;
  --color-ink-muted: #8b7476;
  --color-line: #d2cece;
  --color-primary: #d72836;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #ecd2d4;
  --color-accent: #a26a10;
  --color-accent-ink: #ffffff;
  --color-highlight: #e1d6c6;
  --color-focus: #935c06;
  --color-contrast-surface: #1b0e10;
  --color-contrast-ink: #e7e4e4;
  --color-contrast-line: #483d3f;
  --color-contrast-accent: #e79718;
  --overlay-scrim: linear-gradient(180deg, rgba(27, 14, 16, 0.35) 0%, rgba(27, 14, 16, 0.72) 55%, rgba(27, 14, 16, 0.92) 100%);
  --font-heading: "Songti SC", STSong, "Source Han Serif SC", SimSun, serif;
  --font-body: "Songti SC", STSong, "Source Han Serif SC", SimSun, serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 12.2px;
  --text-sm: 14.6px;
  --text-base: 16px;
  --text-lg: 19.2px;
  --text-xl: 23.0px;
  --text-2xl: 27.6px;
  --text-3xl: 33.2px;
  --text-4xl: 39.8px;
  --text-display: clamp(34px, 6.5vw, 83px);
  --text-figure: clamp(28px, 4.7vw, 60px);
  --weight-heading: 617;
  --weight-body: 400;
  --leading-body: 1.95;
  --leading-heading: 1.22;
  --tracking-heading: 0.019em;
  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 1px;
  --radius-pill: 1px;
  --border-thin: 1px;
  --border-thick: 2px;
  --shadow-1: none;
  --shadow-2: none;
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1120px;
  --measure: 68ch;
  --gutter: 24px;
  --section-y: 92px;
  --section-y-lg: 129px;
}

/* ---------- 1. 重置 ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body, h1, h2, h3, h4, h5, p, ul, ol, li, figure, blockquote, dl, dd, hr { margin: 0; }
ul, ol { padding: 0; list-style: none; }
img, svg, video { display: block; max-width: 100%; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
a { color: inherit; text-decoration: none; }
table { border-collapse: collapse; width: 100%; }
hr { border: 0; }
:focus-visible { outline: 2px solid var(--color-focus); outline-offset: 3px; }
::selection { background: var(--color-primary-soft); color: var(--color-ink); }

body {
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: var(--weight-body);
  line-height: var(--leading-body);
  letter-spacing: 0.01em;
  overflow-x: hidden;
}

/* ---------- 2. 排版 ---------- */
h1, h2, h3, h4, h5, .heading {
  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-3xl); }
h2 { font-size: var(--text-2xl); }
h3 { font-size: var(--text-xl); }
h4 { font-size: var(--text-lg); }
.display-title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 1.04;
  letter-spacing: 0.01em;
}
.u-center { text-align: center; }
.u-mono { font-family: var(--font-mono); }
.u-measure { max-width: var(--measure); }
.u-muted { color: var(--color-ink-muted); }
.u-accent { color: var(--color-accent); }
.figure { font-family: var(--font-mono); font-variant-numeric: tabular-nums; letter-spacing: 0.04em; }
.figure--xl { font-size: var(--text-figure); line-height: 1; }

.prose { max-width: var(--measure); color: var(--color-ink); }
.prose p + p { margin-top: var(--space-2); }
.prose h2 { font-size: var(--text-2xl); margin-top: var(--space-6); margin-bottom: var(--space-2); }
.prose h3 { font-size: var(--text-xl); margin-top: var(--space-4); margin-bottom: var(--space-1); }
.prose ul, .prose ol { margin-top: var(--space-2); }
.prose li { position: relative; padding-left: 20px; margin-bottom: var(--space-1); }
.prose li::before {
  content: ""; position: absolute; left: 0; top: 0.78em;
  width: 8px; height: 1px; background: var(--color-primary);
}
.prose a { color: var(--color-primary); border-bottom: 1px solid var(--color-primary-soft); }
.prose blockquote {
  border-left: 1px solid var(--color-line);
  border-right: 1px solid var(--color-line);
  background: var(--color-surface-alt);
  padding: var(--space-3);
  margin-top: var(--space-3);
  color: var(--color-ink-soft);
}

/* ---------- 3. 容器与栅格 ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
}
.grid { display: grid; gap: var(--gutter); }
.grid--2, .grid--3, .grid--4, .grid--12 { grid-template-columns: 1fr; }
.section { padding-block: var(--space-8); }
.section--tight { padding-block: var(--space-6); }
.section--deep { background: var(--color-contrast-surface); color: var(--color-contrast-ink); }
.section--deep h1, .section--deep h2, .section--deep h3, .section--deep h4 { color: var(--color-contrast-ink); }
.section--deep .prose, .section--deep p { color: var(--color-contrast-ink); }
.section--deep .u-muted { color: color-mix(in srgb, var(--color-contrast-ink) 62%, var(--color-contrast-surface)); }

/* ---------- 4. 边框与分隔语言 ---------- */
.rule-double { border: 0; border-top: 3px double var(--color-line); width: 100%; }
.fret-band {
  display: block;
  width: 100%;
  height: 8px;
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-line);
  border-bottom: 1px solid var(--color-line);
  background-image: repeating-linear-gradient(90deg,
    var(--color-line) 0 1px, transparent 1px 9px,
    var(--color-primary) 9px 12px, transparent 12px 24px);
  background-repeat: repeat;
}
.panel {
  position: relative;
  background: var(--color-surface-alt);
  border: 1px solid var(--color-line);
  padding: var(--space-3);
}
.frame-double {
  position: relative;
  background: var(--color-surface-alt);
  border: 1px solid var(--color-line);
  padding: var(--space-4);
}
.frame-double::after {
  content: "";
  position: absolute;
  inset: 6px;
  border: 1px solid color-mix(in srgb, var(--color-line) 72%, transparent);
  pointer-events: none;
}
.section--deep .frame-double,
.section--deep .panel { border-color: var(--color-contrast-line); background: color-mix(in srgb, var(--color-contrast-surface) 86%, var(--color-contrast-ink)); }
.section--deep .frame-double::after { border-color: var(--color-contrast-line); }
.mark-dot { width: 7px; height: 7px; background: var(--color-primary); display: inline-block; flex: 0 0 auto; }
.mark-diamond { width: 8px; height: 8px; background: var(--color-primary); transform: rotate(45deg); display: inline-block; flex: 0 0 auto; }
.mark-bar { display: inline-block; width: 22px; height: 2px; background: var(--color-primary); }

/* ---------- 5. 章节标题 ---------- */
.section-head { text-align: center; max-width: 760px; margin: 0 auto var(--space-6); }
.section-head__index {
  display: block;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.34em;
  color: var(--color-accent);
  margin-bottom: var(--space-1);
}
.section-head__title { font-size: var(--text-2xl); }
.section-head__note {
  margin-top: var(--space-1);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  letter-spacing: 0.06em;
}
.section-head__rule {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-top: var(--space-2);
}
.section-head__rule::before,
.section-head__rule::after {
  content: "";
  flex: 0 0 72px;
  border-top: 3px double var(--color-line);
}
.section--deep .section-head__index { color: var(--color-contrast-accent); }
.section--deep .section-head__note { color: color-mix(in srgb, var(--color-contrast-ink) 68%, var(--color-contrast-surface)); }
.section--deep .section-head__rule::before,
.section--deep .section-head__rule::after { border-top-color: var(--color-contrast-line); }

.big-index {
  font-family: var(--font-mono);
  font-size: var(--text-4xl);
  line-height: 1;
  letter-spacing: -0.02em;
  color: color-mix(in srgb, var(--color-primary) 52%, var(--color-surface));
  display: block;
}
.section--deep .big-index { color: var(--color-contrast-line); }

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 11px 20px;
  border: 1px solid var(--color-line);
  background: var(--color-surface-alt);
  color: var(--color-ink);
  font-family: var(--font-heading);
  font-size: var(--text-sm);
  letter-spacing: 0.16em;
  line-height: 1.4;
  transition: background-color 200ms ease, border-color 200ms ease, color 200ms ease;
}
.btn:hover { border-color: var(--color-primary); 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) 84%, var(--color-contrast-surface));
  border-color: color-mix(in srgb, var(--color-primary) 84%, var(--color-contrast-surface));
  color: var(--color-primary-ink);
}
.btn--ghost { background: transparent; }
.btn--quiet { padding: 6px 12px; font-size: var(--text-xs); letter-spacing: 0.2em; }
.btn--block { display: flex; width: 100%; justify-content: center; }

/* ---------- 7. 面包屑 ---------- */
.crumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
  padding-block: var(--space-2);
  border-bottom: 1px solid var(--color-line);
}
.crumb__sep { color: var(--color-primary); }
.crumb a:hover { color: var(--color-primary); }
.crumb [aria-current="page"] { color: var(--color-ink); }

/* ---------- 8. 数据岛 ---------- */
.island {
  position: relative;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: 1px solid var(--color-contrast-line);
  padding: var(--space-4);
}
.island::after {
  content: "";
  position: absolute;
  inset: 6px;
  border: 1px solid var(--color-contrast-line);
  pointer-events: none;
}
.island__label {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.24em;
  color: var(--color-contrast-accent);
  display: block;
  margin-bottom: var(--space-2);
}
.metric { position: relative; }
.metric__value {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: var(--text-figure);
  line-height: 0.96;
  letter-spacing: 0.02em;
  color: var(--color-contrast-ink);
}
.metric__value--accent { color: var(--color-contrast-accent); }
.metric__unit { font-size: var(--text-sm); letter-spacing: 0.14em; color: color-mix(in srgb, var(--color-contrast-ink) 72%, var(--color-contrast-surface)); margin-left: 6px; }
.metric__label {
  display: block;
  margin-top: var(--space-1);
  font-size: var(--text-sm);
  letter-spacing: 0.18em;
  color: color-mix(in srgb, var(--color-contrast-ink) 78%, var(--color-contrast-surface));
}
.metric__delta { font-family: var(--font-mono); font-size: var(--text-sm); letter-spacing: 0.04em; }
.metric__delta[data-trend="up"] { color: var(--color-contrast-accent); }
.metric__delta[data-trend="down"] { color: color-mix(in srgb, var(--color-contrast-accent) 58%, var(--color-contrast-ink)); }
.metric__delta[data-trend="flat"] { color: color-mix(in srgb, var(--color-contrast-ink) 62%, var(--color-contrast-surface)); }
.metric--spill .metric__value { margin-right: -0.1em; }

/* ---------- 9. 筛选 ---------- */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: var(--space-2) 0;
  border-top: 1px solid var(--color-line);
  border-bottom: 3px double var(--color-line);
}
.filter-btn {
  padding: 7px 14px;
  border: 1px solid var(--color-line);
  background: var(--color-surface-deep);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  transition: background-color 200ms ease, border-color 200ms ease, color 200ms ease;
}
.filter-btn:hover { border-color: var(--color-primary); color: var(--color-primary); }
.filter-btn[aria-pressed="true"] {
  background: var(--color-primary-soft);
  border-color: var(--color-primary);
  color: var(--color-primary);
}
.filter-btn__count { font-family: var(--font-mono); margin-left: 6px; color: var(--color-ink-muted); }
.filter-status {
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}
[data-filter-item][hidden] { display: none !important; }

/* ---------- 10. 条目列表与悬浮摘要 ---------- */
.entry-list { border-top: 1px solid var(--color-line); }
.entry { border-bottom: 1px solid var(--color-line); position: relative; }
.entry__link {
  display: grid;
  grid-template-columns: auto 1fr auto;
  gap: var(--space-2);
  align-items: baseline;
  padding: var(--space-2) var(--space-2) var(--space-2) var(--space-1);
  transition: background-color 200ms ease;
}
.entry__link:hover { background: var(--color-surface-alt); }
.entry__idx { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-accent); letter-spacing: 0.04em; }
.entry__title { font-family: var(--font-heading); font-size: var(--text-lg); letter-spacing: 0.04em; }
.entry__meta { font-size: var(--text-xs); letter-spacing: 0.16em; color: var(--color-ink-muted); }
.entry__summary {
  display: block;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  transition: max-height 280ms ease, opacity 220ms ease, padding 280ms ease;
}
.entry:hover .entry__summary,
.entry:focus-within .entry__summary {
  max-height: 220px;
  opacity: 1;
  padding-bottom: var(--space-2);
}

/* ---------- 11. 问答折叠 ---------- */
.qa-item { border-bottom: 1px solid var(--color-line); }
.qa-item > summary {
  cursor: pointer;
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: var(--space-2) 0;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  letter-spacing: 0.04em;
  list-style: none;
}
.qa-item > summary::-webkit-details-marker { display: none; }
.qa-item > summary::after {
  content: "＋";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-primary);
}
.qa-item[open] > summary { color: var(--color-primary); }
.qa-item[open] > summary::after { content: "－"; }
.qa-item__no { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-accent); }
.qa-item__body {
  padding: 0 0 var(--space-3) 34px;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

/* ---------- 12. 标签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  border: 1px solid var(--color-line);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  line-height: 1.6;
}
.tag--primary { border-color: var(--color-primary); color: var(--color-primary); background: var(--color-primary-soft); }
.tag--accent { border-color: var(--color-accent); color: var(--color-accent); background: var(--color-highlight); }

/* ---------- 13. 图片容器 ---------- */
.media-block {
  position: relative;
  overflow: hidden;
  background: var(--color-contrast-surface);
  border: 1px solid var(--color-line);
  min-height: 240px;
  display: flex;
  align-items: flex-end;
}
.media-block__img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.media-block__scrim { position: absolute; inset: 0; background: var(--overlay-scrim); }
.media-block__body { position: relative; padding: var(--space-4); color: var(--color-contrast-ink); max-width: var(--measure); }
.media-block__body h2, .media-block__body h3 { color: var(--color-contrast-ink); }
.media-block__caption { font-family: var(--font-mono); font-size: var(--text-xs); letter-spacing: 0.14em; color: var(--color-contrast-accent); display: block; margin-bottom: var(--space-1); }

/* ---------- 14. 头部 ---------- */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 200;
  padding: 10px 18px;
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.16em;
}
.skip-link:focus { left: 8px; top: 8px; }

.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 0;
  background: var(--color-primary);
  z-index: 120;
  transition: width 120ms linear;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-line);
}
.header-util {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: 1px solid var(--color-contrast-line);
  font-size: var(--text-xs);
  line-height: 1.7;
  overflow: hidden;
  max-height: 90px;
  transition: max-height 260ms ease, opacity 200ms ease, border-color 200ms ease;
}
.site-header[data-condensed] .header-util {
  max-height: 0;
  opacity: 0;
  border-bottom-color: transparent;
}
.header-util__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  max-width: var(--container);
  margin-inline: auto;
  padding: 5px var(--gutter);
  flex-wrap: wrap;
}
.header-util__note {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  letter-spacing: 0.14em;
  color: color-mix(in srgb, var(--color-contrast-ink) 84%, var(--color-contrast-surface));
}
.quick-cmd { display: flex; flex-wrap: wrap; gap: var(--space-2); }
.quick-cmd__item { display: block; }
.quick-cmd__link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 2px 9px;
  border: 1px solid var(--color-contrast-line);
  color: var(--color-contrast-ink);
  letter-spacing: 0.1em;
  transition: border-color 200ms ease, color 200ms ease;
}
.quick-cmd__link:hover { border-color: var(--color-contrast-accent); color: var(--color-contrast-accent); }
.quick-cmd__idx { font-family: var(--font-mono); letter-spacing: 0.04em; color: var(--color-contrast-accent); }

.header-main__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  max-width: var(--container);
  margin-inline: auto;
  padding: 10px var(--gutter);
  transition: padding 220ms ease;
}
.site-header[data-condensed] .header-main__inner { padding-block: 6px; }

.brand { display: inline-flex; align-items: center; gap: 10px; flex: 1 1 auto; min-width: 0; }
.brand__seal {
  position: relative;
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  background: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  line-height: 1;
  border: 1px solid var(--color-primary);
}
.brand__seal::after {
  content: "";
  position: absolute;
  inset: 3px;
  border: 1px solid color-mix(in srgb, var(--color-primary-ink) 55%, transparent);
  pointer-events: none;
}
.brand__text { display: flex; flex-direction: column; min-width: 0; }
.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  letter-spacing: 0.16em;
  line-height: 1.2;
  color: var(--color-ink);
}
.brand__sub {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.26em;
  color: var(--color-ink-muted);
  line-height: 1.5;
}

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--color-line);
  background: var(--color-surface-alt);
  color: var(--color-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.18em;
  flex: 0 0 auto;
  transition: border-color 200ms ease, color 200ms ease, background-color 200ms ease;
}
.nav-toggle:hover { border-color: var(--color-primary); color: var(--color-primary); }
.nav-toggle__bars {
  width: 16px;
  height: 11px;
  display: inline-block;
  border-top: 2px solid var(--color-primary);
  border-bottom: 2px solid var(--color-primary);
}
.nav-toggle[aria-expanded="true"] {
  border-color: var(--color-primary);
  background: var(--color-primary-soft);
  color: var(--color-primary);
}

.site-nav { display: none; width: 100%; }
.site-nav[data-open] { display: block; }
.site-nav__list {
  display: flex;
  flex-direction: column;
  margin-top: var(--space-1);
  border-top: 1px solid var(--color-line);
}
.site-nav__item { display: block; }
.site-nav__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 11px 2px;
  border-bottom: 1px solid var(--color-line);
  font-size: var(--text-sm);
  letter-spacing: 0.16em;
  color: var(--color-ink);
  position: relative;
  transition: color 200ms ease;
}
.site-nav__link:hover { color: var(--color-primary); }
.site-nav__idx {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-accent);
}
.site-nav__link[aria-current="page"] { color: var(--color-primary); }
.site-nav__link[aria-current="page"] .site-nav__idx { color: var(--color-primary); }

/* ---------- 15. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: var(--section-y);
  padding-block: var(--space-6) var(--space-4);
  background: var(--color-surface);
  border-top: 1px solid var(--color-line);
}
.site-footer .fret-band { margin-bottom: var(--space-6); }
.site-footer__inner { padding-inline: var(--gutter); }
.footer-grid { display: grid; grid-template-columns: 1fr; gap: var(--space-3); }
.footer-panel {
  position: relative;
  background: var(--color-surface-alt);
  border: 1px solid var(--color-line);
  padding: var(--space-3);
}
.footer-panel::after {
  content: "";
  position: absolute;
  inset: 5px;
  border: 1px solid color-mix(in srgb, var(--color-line) 70%, transparent);
  pointer-events: none;
}
.footer-panel__title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: var(--text-sm);
  letter-spacing: 0.3em;
  color: var(--color-ink);
  padding-bottom: 8px;
  margin-bottom: var(--space-2);
  border-bottom: 3px double var(--color-line);
}
.footer-panel__title::before {
  content: "";
  width: 10px;
  height: 2px;
  background: var(--color-primary);
  flex: 0 0 auto;
}
.footer-panel__lead {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  letter-spacing: 0.14em;
  color: var(--color-ink);
  line-height: 1.3;
}
.footer-panel__text {
  margin-top: var(--space-1);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  line-height: 1.8;
}
.footer-panel__note {
  margin-top: var(--space-2);
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
  line-height: 1.8;
}
.footer-meta {
  display: flex;
  gap: 10px;
  align-items: baseline;
  margin-top: 8px;
  padding-top: 8px;
  border-top: 1px solid color-mix(in srgb, var(--color-line) 70%, transparent);
  font-size: var(--text-xs);
}
.footer-meta__key { letter-spacing: 0.24em; color: var(--color-ink-muted); flex: 0 0 auto; }
.footer-meta__val { font-family: var(--font-mono); letter-spacing: 0.04em; color: var(--color-ink); }
.contact-row {
  display: grid;
  grid-template-columns: 4.4em 1fr;
  gap: 8px;
  padding: 7px 0;
  border-bottom: 1px solid color-mix(in srgb, var(--color-line) 72%, transparent);
}
.contact-row__label { font-size: var(--text-xs); letter-spacing: 0.24em; color: var(--color-ink-muted); }
.contact-row__value { font-size: var(--text-sm); color: var(--color-ink); word-break: break-word; }
.contact-row__value--mono { font-family: var(--font-mono); letter-spacing: 0.04em; }
.contact-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: var(--space-2); }
.copy-btn {
  padding: 6px 12px;
  border: 1px solid var(--color-line);
  background: var(--color-surface);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  transition: border-color 200ms ease, color 200ms ease, background-color 200ms ease;
}
.copy-btn:hover { border-color: var(--color-primary); color: var(--color-primary); }
.copy-btn[data-copied="true"] {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: var(--color-highlight);
}
.copy-status { margin-top: 8px; font-size: var(--text-xs); letter-spacing: 0.1em; color: var(--color-ink-muted); min-height: 1.5em; }
.footer-links { display: block; }
.footer-links__item { display: block; }
.footer-links__link {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 0;
  border-bottom: 1px solid color-mix(in srgb, var(--color-line) 72%, transparent);
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  color: var(--color-ink);
  transition: color 200ms ease, padding-left 200ms ease;
}
.footer-links__link:hover { color: var(--color-primary); padding-left: 6px; }
.footer-links__idx { font-family: var(--font-mono); font-size: var(--text-xs); color: var(--color-accent); letter-spacing: 0.04em; }
.footer-base {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  margin-top: var(--space-6);
  padding-top: var(--space-2);
  border-top: 3px double var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}
.footer-base__copy { color: var(--color-ink-soft); }
.footer-base__icp { font-family: var(--font-mono); letter-spacing: 0.06em; }

/* ---------- 16. 返回顶部与显现 ---------- */
.to-top {
  position: fixed;
  right: var(--space-2);
  bottom: var(--space-2);
  z-index: 110;
  padding: 9px 14px;
  border: 1px solid var(--color-line);
  background: var(--color-surface-alt);
  color: var(--color-ink);
  font-size: var(--text-xs);
  letter-spacing: 0.2em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 220ms ease, transform 220ms ease, visibility 220ms ease, border-color 200ms ease, color 200ms ease;
}
.to-top[data-visible] { opacity: 1; visibility: visible; transform: none; }
.to-top:hover { border-color: var(--color-primary); color: var(--color-primary); }

.reveal { transition: opacity 320ms ease, transform 320ms ease; }
html[data-reveal="on"] .reveal { opacity: 0; transform: translate3d(0, 14px, 0); }
html[data-reveal="on"] .reveal.is-visible { opacity: 1; transform: none; }

/* ---------- 17. 响应式 ---------- */
@media (max-width: 639px) {
  .header-util__note { display: none; }
  .header-util__inner { justify-content: center; }
  .brand__sub { display: none; }
}
@media (min-width: 720px) {
  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .section-head__title { font-size: var(--text-3xl); }
}
@media (min-width: 900px) {
  .nav-toggle { display: none; }
  .brand { flex: 0 0 auto; }
  .site-nav { display: flex; width: auto; margin-left: auto; }
  .site-nav__list {
    flex-direction: row;
    align-items: center;
    gap: var(--space-3);
    margin-top: 0;
    border-top: 0;
  }
  .site-nav__link {
    padding: 6px 0 8px;
    border-bottom: 0;
  }
  .site-nav__link::after {
    content: "";
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    height: 2px;
    background: var(--color-primary);
    transform: scaleX(0);
    transform-origin: center;
    transition: transform 220ms ease;
  }
  .site-nav__link:hover::after,
  .site-nav__link[aria-current="page"]::after { transform: scaleX(1); }
}
@media (min-width: 1024px) {
  .section { padding-block: var(--section-y); }
  .section--tight { padding-block: var(--space-8); }
  .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .grid--12 { grid-template-columns: repeat(12, minmax(0, 1fr)); }
  .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; }
  .footer-grid { grid-template-columns: 1.15fr 1.05fr 0.9fr 1fr; }
}

/* ---------- 18. 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
  html[data-reveal="on"] .reveal { opacity: 1; transform: none; }
}