.page-about {
  --ab-rule: var(--sand-line);
  --ab-gutter: clamp(22px, 3.4vw, 40px);
  background: var(--sand);
  color: var(--ink);
  font-family: var(--font-body);
  padding-block: clamp(24px, 4vw, 44px) clamp(56px, 9vw, 120px);
  overflow-x: hidden;
}

.page-about .crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 12.5px;
  letter-spacing: .06em;
  color: var(--ink-mute);
  margin-bottom: clamp(20px, 3.2vw, 34px);
}

.page-about .crumbs .crumb {
  color: var(--ink-mute);
  text-decoration: none;
}

.page-about .crumbs a.crumb:hover,
.page-about .crumbs a.crumb:focus-visible {
  color: var(--danxia);
}

.page-about .crumbs .crumb[aria-current="page"] {
  color: var(--danxia);
  font-weight: 700;
}

.page-about .crumb-sep {
  color: var(--ab-rule);
}

/* ---------- 首屏 ---------- */

.page-about .ab-hero {
  position: relative;
  padding-bottom: clamp(28px, 4.6vw, 52px);
  border-bottom: 1px solid var(--ab-rule);
}

.page-about .ab-hero::before {
  content: "";
  display: block;
  width: 68px;
  height: 3px;
  background: linear-gradient(90deg, var(--danxia) 0%, var(--gold) 100%);
  margin-bottom: clamp(20px, 3vw, 34px);
}

.page-about .ab-hero .eyebrow {
  margin: 0 0 12px;
  color: var(--danxia);
  letter-spacing: .18em;
}

.page-about .ab-h1 {
  font-family: var(--font-display);
  font-weight: 850;
  font-size: clamp(30px, 7.4vw, 66px);
  line-height: 1.09;
  letter-spacing: -0.03em;
  margin: 0 0 clamp(16px, 2.4vw, 26px);
  max-width: 20ch;
  text-wrap: balance;
}

.page-about .ab-h1 em {
  font-style: normal;
  color: var(--danxia);
  background-image: linear-gradient(transparent 64%, var(--gold-light) 64%, var(--gold-light) 90%, transparent 90%);
}

.page-about .ab-lead {
  font-size: clamp(15.5px, 1.7vw, 18px);
  line-height: 1.8;
  color: var(--ink-soft);
  max-width: 40em;
  margin: 0 0 clamp(26px, 4vw, 42px);
}

.page-about .ab-hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--ab-rule);
  border: 1px solid var(--ab-rule);
  margin: 0;
}

.page-about .ab-hero-stat {
  background: var(--sand);
  padding: clamp(14px, 2vw, 22px) clamp(12px, 1.8vw, 20px);
}

.page-about .ab-hero-stat dt {
  font-size: 11.5px;
  letter-spacing: .12em;
  color: var(--ink-mute);
  margin-bottom: 8px;
}

.page-about .ab-hero-stat dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(21px, 2.6vw, 30px);
  font-weight: 700;
  line-height: 1;
  color: var(--stat-color);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.02em;
}

.page-about .ab-hero-stat dd span {
  font-family: var(--font-body);
  font-size: .46em;
  font-weight: 500;
  color: var(--ink-mute);
  margin-left: 4px;
  letter-spacing: 0;
}

@media (min-width: 720px) {
  .page-about .ab-hero-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* ---------- 阶梯目录 ---------- */

.page-about .ab-toc {
  padding: clamp(22px, 3.4vw, 38px) 0;
  border-bottom: 1px solid var(--ab-rule);
}

.page-about .ab-toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px 14px;
}

.page-about .ab-toc-link {
  display: block;
  padding: 10px 0 12px;
  text-decoration: none;
  color: var(--ink-soft);
  border-top: 2px solid var(--ab-rule);
  transition: border-color 160ms ease, color 160ms ease;
}

.page-about .ab-toc-link:hover,
.page-about .ab-toc-link:focus-visible {
  border-top-color: var(--gold);
  color: var(--danxia-deep);
}

.page-about .ab-toc-num {
  display: block;
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: .16em;
  color: var(--danxia);
  margin-bottom: 5px;
}

.page-about .ab-toc-text {
  display: block;
  font-size: 13px;
  line-height: 1.45;
  font-weight: 650;
}

@media (min-width: 700px) {
  .page-about .ab-toc-list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px 18px;
  }
}

@media (min-width: 1024px) {
  .page-about .ab-toc-list {
    grid-template-columns: repeat(6, minmax(0, 1fr));
    gap: 0 16px;
    align-items: start;
  }

  .page-about .ab-toc-item:nth-child(2) { margin-top: 12px; }
  .page-about .ab-toc-item:nth-child(3) { margin-top: 24px; }
  .page-about .ab-toc-item:nth-child(4) { margin-top: 36px; }
  .page-about .ab-toc-item:nth-child(5) { margin-top: 24px; }
  .page-about .ab-toc-item:nth-child(6) { margin-top: 12px; }
}

/* ---------- 章节 ---------- */

.page-about .ab-chapter {
  padding-top: clamp(40px, 6.4vw, 84px);
  padding-bottom: clamp(34px, 5vw, 68px);
  scroll-margin-top: calc(var(--cmd-h) + 20px);
}

.page-about .ab-cnum {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .2em;
  color: var(--danxia);
  margin: 0 0 10px;
}

.page-about .ab-ctitle {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(24px, 4.2vw, 44px);
  line-height: 1.16;
  letter-spacing: -0.02em;
  margin: 0 0 clamp(20px, 3.2vw, 36px);
  max-width: 22ch;
  color: var(--ink);
}

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

@media (min-width: 900px) {
  .page-about .ab-grid {
    grid-template-columns: minmax(0, 1.85fr) minmax(190px, .8fr);
    gap: clamp(32px, 4.6vw, 72px);
    align-items: start;
  }
}

.page-about .ab-narrative p {
  font-size: clamp(15.5px, 1.5vw, 17px);
  line-height: 1.86;
  color: var(--ink-soft);
  margin: 0 0 1.15em;
  max-width: 36em;
}

.page-about .ab-narrative p:last-child {
  margin-bottom: 0;
}

.page-about .ab-narrative strong {
  color: var(--danxia-deep);
  font-weight: 700;
}

/* ---------- 旁注 ---------- */

.page-about .ab-side {
  border-top: 1px solid var(--ab-rule);
  padding-top: 16px;
}

@media (min-width: 900px) {
  .page-about .ab-side {
    border-top: 0;
    border-left: 1px solid var(--ab-rule);
    padding-top: 0;
    padding-left: clamp(18px, 2.2vw, 30px);
  }
}

.page-about .ab-side-label {
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--ink-mute);
  margin: 0 0 10px;
}

.page-about .ab-side-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: clamp(30px, 4.2vw, 46px);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--stat-color);
  font-variant-numeric: tabular-nums;
  margin: 0 0 12px;
  padding-bottom: 3px;
  border-bottom: 2px solid var(--gold-light);
  cursor: help;
}

.page-about .ab-side-note {
  font-size: 13px;
  line-height: 1.72;
  color: var(--ink-mute);
  margin: 0;
  max-width: 26em;
}

.page-about .ab-side-facts {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-side-fact {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--ab-rule);
}

.page-about .ab-side-fact:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .ab-fact-num {
  font-family: var(--font-mono);
  font-size: clamp(22px, 2.6vw, 30px);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--stat-color);
  font-variant-numeric: tabular-nums;
  cursor: help;
}

.page-about .ab-fact-txt {
  font-size: 13px;
  line-height: 1.5;
  color: var(--ink-mute);
}

/* ---------- 经纬示意 ---------- */

.page-about .ab-coord {
  display: block;
  width: clamp(76px, 12vw, 104px);
  height: auto;
  color: var(--danxia);
  margin: 0 0 18px;
  opacity: .8;
}

/* ---------- 图片 ---------- */

.page-about .ab-figure {
  margin: 0 0 clamp(22px, 3.4vw, 40px);
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--ab-rule);
  background: var(--sand-line);
}

.page-about .ab-figure--wide img { aspect-ratio: 1920 / 1080; }
.page-about .ab-figure--tall img { aspect-ratio: 1200 / 800; }
.page-about .ab-figure--closing img { aspect-ratio: 1600 / 900; }

.page-about .ab-figure .figure-caption {
  margin-top: 10px;
  padding-left: 10px;
  border-left: 2px solid var(--gold);
  font-size: 12.5px;
  line-height: 1.6;
  color: var(--ink-mute);
}

/* ---------- 章节间色带 ---------- */

.page-about .ab-band {
  height: 3px;
  border: 0;
  margin: 0;
  background: linear-gradient(90deg,
    var(--danxia) 0%,
    var(--gold) 26%,
    var(--pitch-light) 58%,
    var(--night) 100%);
  opacity: .75;
}

/* ---------- 收尾 ---------- */

.page-about .ab-closing {
  margin-top: clamp(44px, 7vw, 88px);
  padding: clamp(30px, 5vw, 62px) clamp(20px, 4vw, 56px);
  background: var(--night);
  color: var(--sand);
  border-radius: var(--radius);
  scroll-margin-top: calc(var(--cmd-h) + 20px);
}

.page-about .ab-closing .ab-cnum {
  color: var(--gold);
}

.page-about .ab-closing-title {
  color: var(--sand);
}

.page-about .ab-closing .ab-figure {
  margin-bottom: clamp(24px, 3.6vw, 40px);
}

.page-about .ab-closing .ab-figure img {
  border-color: rgba(244, 238, 226, .18);
}

.page-about .ab-closing-lead {
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.85;
  color: rgba(244, 238, 226, .76);
  max-width: 38em;
  margin: 0 0 1.1em;
}

.page-about .ab-closing-lead:last-of-type {
  margin-bottom: 0;
}

.page-about .ab-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(24px, 3.6vw, 36px);
}

.page-about .ab-closing .btn-ghost {
  color: var(--sand);
  border-color: rgba(244, 238, 226, .38);
}

.page-about .ab-closing .btn-ghost:hover,
.page-about .ab-closing .btn-ghost:focus-visible {
  color: var(--night);
  background: var(--sand);
  border-color: var(--sand);
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-toc-link {
    transition: none;
  }
}
</main>