:root {
  --color-surface: #f6f5f4;
  --color-surface-alt: #eeeceb;
  --color-surface-deep: #e2e0de;
  --color-ink: #4e453c;
  --color-ink-soft: #75695c;
  --color-ink-muted: #8d8072;
  --color-line: #d8d5d3;
  --color-primary: #956d42;
  --color-primary-ink: #ffffff;
  --color-primary-soft: #e8e2db;
  --color-accent: #c94e0d;
  --color-accent-ink: #ffffff;
  --color-highlight: #eed7ca;
  --color-focus: #c04402;
  --color-contrast-surface: #28231c;
  --color-contrast-ink: #e7e6e4;
  --color-contrast-line: #524e48;
  --color-contrast-accent: #f05d0f;
  --overlay-scrim: linear-gradient(180deg, rgba(40, 35, 28, 0.35) 0%, rgba(40, 35, 28, 0.72) 55%, rgba(40, 35, 28, 0.92) 100%);
  --font-heading: STZhongsong, "Source Han Serif SC", "Songti SC", SimSun, serif;
  --font-body: "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, Menlo, Consolas, monospace;
  --text-xs: 9.5px;
  --text-sm: 13.5px;
  --text-base: 16px;
  --text-lg: 22.6px;
  --text-xl: 32.0px;
  --text-2xl: 45.2px;
  --text-3xl: 64.0px;
  --text-4xl: 90.4px;
  --text-display: clamp(40px, 8.3vw, 106px);
  --text-figure: clamp(33px, 5.9vw, 76px);
  --weight-heading: 719;
  --weight-body: 400;
  --leading-body: 1.74;
  --leading-heading: 1.17;
  --tracking-heading: 0.008em;
  --radius-sm: 0px;
  --radius-md: 0px;
  --radius-lg: 0px;
  --radius-pill: 0px;
  --border-thin: 1px;
  --border-thick: 1px;
  --shadow-1: 0 1px 0 rgba(78, 69, 60, 0.12);
  --shadow-2: 0 2px 0 rgba(78, 69, 60, 0.18);
  --space-1: 8px;
  --space-2: 16px;
  --space-3: 24px;
  --space-4: 32px;
  --space-6: 48px;
  --space-8: 64px;
  --container: 1020px;
  --measure: 69ch;
  --gutter: 16px;
  --section-y: 91px;
  --section-y-lg: 127px;
}

/* ============================================================
   1. reset
   ============================================================ */
*,
*::before,
*::after { box-sizing: border-box; }

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

body {
  margin: 0;
  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);
  -webkit-font-smoothing: antialiased;
}

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

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

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

button { border-radius: var(--radius-sm); }

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

h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd, hr { margin: 0; }

hr { border: 0; }

/* ============================================================
   2. 中文排版
   ============================================================ */
h1, h2, h3, h4 {
  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;
}

h1 { font-size: var(--text-2xl); }
h2 { font-size: var(--text-xl); }
h3 { font-size: var(--text-lg); }
h4 { font-size: var(--text-base); }

p { text-wrap: pretty; }

.mono,
code, kbd, samp, pre {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
}

strong { font-weight: 600; }

.display-title {
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 0.98;
  letter-spacing: 0.02em;
  text-align: center;
  color: var(--color-ink);
}

.figure-num {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 1;
  letter-spacing: -0.01em;
  color: var(--color-accent);
}

/* ============================================================
   3. 容器 / 栅格 / 分区
   ============================================================ */
.container {
  width: 100%;
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
}

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

.col-2 { grid-column: span 2; }
.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-9 { grid-column: span 9; }
.col-12 { grid-column: span 12; }

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

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

.lede {
  font-size: var(--text-lg);
  line-height: 1.6;
  color: var(--color-ink-soft);
}

.section { padding-block: var(--section-y); }
.section--lg { padding-block: var(--section-y-lg); }
.section--alt { background-color: var(--color-surface-alt); }
.section--deep { background-color: var(--color-surface-deep); }

.section--contrast,
.on-dark {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.section--contrast h1,
.section--contrast h2,
.section--contrast h3,
.section--contrast h4,
.on-dark h1, .on-dark h2, .on-dark h3, .on-dark h4 { color: var(--color-contrast-ink); }

.section--contrast .sec-head,
.on-dark .sec-head { border-bottom-color: var(--color-contrast-line); }

.section--contrast .rule-dot,
.on-dark .rule-dot { border-top-color: var(--color-contrast-line); }

/* ============================================================
   4. 章节头 / 印刷分隔
   ============================================================ */
.sec-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-1) var(--space-2);
  padding-bottom: var(--space-2);
  margin-bottom: var(--space-4);
  border-bottom: 3px double var(--color-line);
}

.sec-head--center {
  flex-direction: column;
  align-items: center;
  text-align: center;
  border-bottom: 0;
  padding-bottom: 0;
}

.sec-num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.18em;
  color: var(--color-accent);
}

.sec-title {
  font-size: var(--text-xl);
  margin: 0;
}

.sec-kicker {
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.rule-dot { border-top: 1px dotted var(--color-line); margin-block: var(--space-3); }
.rule-dash { border-top: 1px dashed var(--color-line); margin-block: var(--space-3); }
.rule-double { border-top: 3px double var(--color-line); margin-block: var(--space-4); }

/* ============================================================
   5. 标签 / 徽标 / 按钮 / 边框
   ============================================================ */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  border: var(--border-thin) solid var(--color-line);
  background-color: var(--color-primary-soft);
  color: var(--color-ink);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.5;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  white-space: nowrap;
}

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

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

.tag--outline {
  background-color: transparent;
  border-color: var(--color-line);
  color: var(--color-ink-soft);
}

.badge {
  display: inline-grid;
  place-items: center;
  min-width: 34px;
  height: 34px;
  padding: 0 6px;
  border: var(--border-thin) solid var(--color-primary);
  background-color: var(--color-primary-soft);
  color: var(--color-primary);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-1);
  padding: 10px var(--space-2);
  border: var(--border-thin) solid var(--color-ink);
  background-color: transparent;
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: 0.08em;
  cursor: pointer;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}

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

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

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

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

.btn--block {
  width: 100%;
}

.frame-double {
  position: relative;
  border: var(--border-thin) solid var(--color-primary);
  padding: var(--space-3);
}

.frame-double::after {
  content: "";
  position: absolute;
  inset: 4px;
  border: var(--border-thin) solid var(--color-primary);
  pointer-events: none;
}

/* ============================================================
   6. 刊头 site-header
   ============================================================ */
.skip-link {
  position: absolute;
  left: var(--space-2);
  top: -80px;
  z-index: 200;
  padding: var(--space-1) var(--space-2);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  transition: top 0.18s ease;
}

.skip-link:focus { top: var(--space-2); }

.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background-color: transparent;
  z-index: 120;
  pointer-events: none;
}

.scroll-progress > span {
  display: block;
  height: 100%;
  width: 0;
  background-color: var(--color-accent);
}

.site-header {
  position: relative;
  z-index: 80;
  background-color: var(--color-surface);
  border-bottom: 3px double var(--color-primary);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding-block: var(--space-3);
}

.brand-block { display: flex; align-items: center; min-width: 0; }

.brand {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  min-width: 0;
}

.brand__mark {
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  flex: 0 0 auto;
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  border: var(--border-thin) solid var(--color-ink);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
}

.brand__text { display: flex; flex-direction: column; gap: 2px; min-width: 0; }

.brand__name {
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: 1.2;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.brand__line {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.16em;
  color: var(--color-ink-muted);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: var(--space-1);
  padding: 8px 12px;
  border: var(--border-thin) solid var(--color-ink);
  background-color: var(--color-surface);
  color: var(--color-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  cursor: pointer;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 16px;
  height: 10px;
  border-top: 1px solid currentColor;
  border-bottom: 1px solid currentColor;
}

.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 4px;
  border-top: 1px solid currentColor;
}

.nav-toggle__text { display: inline; }

.nav-toggle[aria-expanded="true"] {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}

.site-nav { display: flex; }

.nav-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 2px;
}

.nav-item { display: block; }

.nav-link {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 6px;
  padding: 8px 10px;
  border: var(--border-thin) solid transparent;
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  transition: color 0.18s ease, background-color 0.18s ease, border-color 0.18s ease;
}

.nav-link:hover {
  color: var(--color-ink);
  background-color: var(--color-surface-alt);
  border-color: var(--color-line);
}

.nav-num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.nav-num::before {
  content: "";
  display: none;
  width: 6px;
  height: 6px;
  margin-right: 6px;
  background-color: var(--color-accent);
}

.nav-text { display: inline; }

.nav-link[aria-current="page"] {
  color: var(--color-ink);
  background-color: var(--color-highlight);
  border-color: var(--color-accent);
}

.nav-link[aria-current="page"] .nav-num { color: var(--color-accent); }

.nav-link[aria-current="page"] .nav-num::before { display: inline-block; }

/* ============================================================
   7. 赛事周期索引条
   ============================================================ */
.index-bar {
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thin) solid var(--color-contrast-line);
}

.index-bar__inner {
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space-3);
  display: flex;
  align-items: stretch;
  gap: var(--space-3);
}

.index-bar__lead {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  flex: 0 0 auto;
  padding-block: var(--space-2);
}

.index-bar__hint {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-contrast-ink);
  opacity: 0.68;
  white-space: nowrap;
}

.index-track {
  display: flex;
  flex: 1 1 auto;
  min-width: 0;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
  border-left: var(--border-thin) solid var(--color-contrast-line);
}

.index-track::-webkit-scrollbar { height: 6px; }
.index-track::-webkit-scrollbar-track { background-color: var(--color-contrast-surface); }
.index-track::-webkit-scrollbar-thumb { background-color: var(--color-contrast-line); }

.index-cell {
  flex: 0 0 auto;
  min-width: 200px;
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: var(--space-2) var(--space-3);
  border-right: var(--border-thin) solid var(--color-contrast-line);
  scroll-snap-align: start;
}

.index-cell__num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-contrast-ink);
  opacity: 0.62;
}

.index-cell__label {
  font-family: var(--font-heading);
  font-size: var(--text-base);
  line-height: 1.3;
  letter-spacing: var(--tracking-heading);
  color: var(--color-contrast-ink);
}

.index-cell__meta {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-contrast-ink);
  opacity: 0.7;
}

.index-cell.is-current {
  background-color: color-mix(in srgb, var(--color-contrast-accent) 14%, transparent);
  box-shadow: inset 0 -3px 0 var(--color-contrast-accent);
}

.index-cell.is-current .index-cell__num { color: var(--color-contrast-accent); opacity: 1; }
.index-cell.is-current .index-cell__label { color: var(--color-contrast-accent); }

.index-bar__cta {
  flex: 0 0 auto;
  align-self: center;
  margin-block: var(--space-2);
}

/* ============================================================
   8. 页脚
   ============================================================ */
.site-footer {
  margin-top: var(--section-y);
  background-color: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: 3px double var(--color-primary);
}

.site-footer__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2) var(--space-3);
  padding-block: var(--space-3);
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.footer-mark {
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  background-color: var(--color-primary);
  color: var(--color-primary-ink);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1;
}

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

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-3);
}

.footer-link {
  padding-bottom: 2px;
  border-bottom: 1px dotted var(--color-contrast-line);
  color: var(--color-contrast-ink);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  transition: color 0.18s ease, border-color 0.18s ease;
}

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

.footer-meta {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-contrast-ink);
  opacity: 0.74;
}

.site-footer__contact { border-top: var(--border-thin) solid var(--color-contrast-line); }

.footer-contact__inner {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-3);
  padding-block: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-contrast-ink);
  opacity: 0.78;
}

.footer-contact__item { display: inline-block; }

/* ============================================================
   9. 通用组件
   ============================================================ */
.card {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-3);
  background-color: var(--color-surface);
  border: var(--border-thin) solid var(--color-line);
  transition: background-color 0.18s ease, box-shadow 0.18s ease, border-color 0.18s ease;
}

.card:hover {
  background-color: var(--color-surface-alt);
  box-shadow: var(--shadow-2);
}

.card--accent { border-color: var(--color-accent); }

.card__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
}

.card__num {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.card__title {
  font-size: var(--text-lg);
  margin: 0;
}

.card__meta {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.card__body {
  font-size: var(--text-sm);
  line-height: 1.72;
  color: var(--color-ink-soft);
}

.card__foot {
  margin-top: auto;
  padding-top: var(--space-2);
  border-top: 1px dotted var(--color-line);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-1) var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.figure {
  margin: 0;
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
}

.figure__frame {
  position: relative;
  overflow: hidden;
  aspect-ratio: 4 / 3;
  background-color: var(--color-surface-deep);
}

.figure__frame--wide { aspect-ratio: 16 / 9; }
.figure__frame--tall { aspect-ratio: 3 / 4; }
.figure__frame--square { aspect-ratio: 1 / 1; }

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

.figure--scrim .figure__frame::after {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
}

.figure__overlay {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 2;
  padding: var(--space-3);
  color: var(--color-contrast-ink);
}

.figure__cap {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--space-1) var(--space-2);
  padding: var(--space-1) var(--space-2);
  border-top: 1px dotted var(--color-line);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

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

.table-print caption {
  padding-bottom: var(--space-2);
  text-align: left;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-ink-muted);
}

.table-print th,
.table-print td {
  border: var(--border-thin) solid var(--color-line);
  padding: var(--space-1) var(--space-2);
  text-align: left;
  vertical-align: top;
}

.table-print thead th {
  background-color: var(--color-surface-deep);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: 600;
  letter-spacing: 0.12em;
  color: var(--color-ink-soft);
}

.table-print tbody tr:nth-child(even) { background-color: var(--color-surface-alt); }

.table-print td.num {
  font-family: var(--font-mono);
  color: var(--color-accent);
}

.note {
  padding: var(--space-2) var(--space-3);
  border-left: 3px solid var(--color-accent);
  background-color: var(--color-highlight);
  font-size: var(--text-sm);
  line-height: 1.72;
  color: var(--color-ink);
}

.note__label {
  display: block;
  margin-bottom: var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.14em;
  color: var(--color-accent);
}

.toc {
  padding: var(--space-3);
  border: 3px double var(--color-line);
  background-color: var(--color-surface-alt);
}

.toc__title {
  margin-bottom: var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.18em;
  color: var(--color-ink-muted);
}

.toc__list { display: grid; }

.toc__item { border-top: 1px dotted var(--color-line); }
.toc__item:first-child { border-top: 0; }

.toc__link {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  padding: var(--space-1);
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  transition: background-color 0.18s ease, color 0.18s ease;
}

.toc__link:hover {
  background-color: var(--color-highlight);
  color: var(--color-ink);
}

.toc__link[aria-current="true"] {
  background-color: var(--color-highlight);
  color: var(--color-ink);
}

.toc__num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-accent);
}

.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-2);
  background-color: var(--color-surface-alt);
  border: var(--border-thin) solid var(--color-line);
  border-left: 3px solid var(--color-primary);
}

.filter-btn {
  padding: 6px 12px;
  border: var(--border-thin) solid var(--color-line);
  background-color: var(--color-surface);
  color: var(--color-ink-soft);
  font-size: var(--text-sm);
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}

.filter-btn:hover {
  background-color: var(--color-highlight);
  color: var(--color-ink);
  border-color: var(--color-accent);
}

.filter-btn[aria-pressed="true"] {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: var(--color-accent-ink);
}

.filter-count {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.breadcrumb {
  padding-block: var(--space-2);
  border-bottom: 1px dotted var(--color-line);
}

.breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-1);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

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

.breadcrumb__item::after {
  content: "／";
  color: var(--color-line);
}

.breadcrumb__item:last-child::after { content: ""; }

.breadcrumb__item a { transition: color 0.18s ease; }
.breadcrumb__item a:hover { color: var(--color-accent); }

.breadcrumb__current { color: var(--color-ink); }

.is-hidden { display: none !important; }

.reveal {
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

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

/* ============================================================
   10. 可访问性
   ============================================================ */
:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 2px;
}

.site-footer :focus-visible,
.index-bar :focus-visible,
.on-dark :focus-visible,
.section--contrast :focus-visible { outline-color: var(--color-contrast-accent); }

/* ============================================================
   11. 响应式
   ============================================================ */
@media (max-width: 1080px) {
  .index-cell { min-width: 180px; }
}

@media (max-width: 960px) {
  .section { padding-block: calc(var(--section-y) * 0.6); }
  .section--lg { padding-block: calc(var(--section-y-lg) * 0.6); }

  .site-header__inner {
    flex-wrap: wrap;
    padding-block: var(--space-2);
  }

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

  .site-nav {
    display: none;
    flex-basis: 100%;
    width: 100%;
    margin-top: var(--space-2);
    padding-top: var(--space-2);
    border-top: 1px dotted var(--color-line);
  }

  .site-nav[data-open] { display: block; }

  .nav-list { flex-direction: column; align-items: stretch; gap: 0; }

  .nav-link {
    justify-content: flex-start;
    padding: 12px 4px;
    border: 0;
    border-bottom: 1px dotted var(--color-line);
    font-size: var(--text-base);
  }

  .nav-link:hover { background-color: transparent; border-color: transparent; border-bottom-color: var(--color-accent); }

  .nav-link[aria-current="page"] {
    background-color: transparent;
    border-color: transparent;
    border-bottom-color: var(--color-accent);
  }

  .index-bar__inner {
    flex-direction: column;
    align-items: stretch;
    gap: var(--space-1);
  }

  .index-bar__lead { padding-bottom: 0; }

  .index-track {
    border-left: 0;
    border-top: var(--border-thin) solid var(--color-contrast-line);
  }

  .index-bar__cta {
    align-self: flex-start;
    margin: var(--space-1) 0 var(--space-2);
  }

  .site-footer { margin-top: var(--space-8); }
}

@media (max-width: 700px) {
  .container { padding-inline: var(--space-2); }
  .index-bar__inner { padding-inline: var(--space-2); }

  .section { padding-block: var(--space-6); }
  .section--lg { padding-block: var(--space-8); }

  .grid-12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }
  .grid-12 > [class*="col-"] { grid-column: span 6; }

  .brand__mark { width: 38px; height: 38px; font-size: var(--text-base); }
  .brand__name { font-size: var(--text-base); }
  .brand__line { letter-spacing: 0.1em; }

  .sec-head { margin-bottom: var(--space-3); }
  .sec-title { font-size: var(--text-lg); }

  .frame-double { padding: var(--space-2); }
  .card { padding: var(--space-2); }

  .site-footer__inner { flex-direction: column; align-items: flex-start; }
  .footer-contact__inner { flex-direction: column; }
}

/* ============================================================
   12. 动效降级
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    transition-duration: 0.001ms !important;
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
  }

  .reveal { opacity: 1; transform: none; }
}