.page-about {
  --about-rail-top: calc(var(--header-h) + 28px);
  padding-bottom: clamp(48px, 8vw, 96px);
}

/* 面包屑 */
.page-about .breadcrumb {
  padding-top: clamp(18px, 3vw, 28px);
}
.page-about .breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--mist);
}
.page-about .breadcrumb-item + .breadcrumb-item::before {
  content: "/";
  margin-right: 8px;
  color: var(--slate);
}
.page-about .breadcrumb-item a {
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.25s var(--ease), border-color 0.25s var(--ease);
}
.page-about .breadcrumb-item a:hover,
.page-about .breadcrumb-item a:focus-visible {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

/* 首屏 */
.page-about .about-hero {
  padding-top: clamp(24px, 5vw, 48px);
}
.page-about .hero-copy h1 {
  margin: 14px 0 0;
  max-width: 20ch;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(32px, 6vw, 58px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--ink);
}
.page-about .hero-copy .lede {
  margin: 20px 0 0;
  max-width: 62ch;
  font-size: clamp(16px, 2.1vw, 17px);
  line-height: 1.75;
  color: var(--mist);
}
.page-about .eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.12em;
  color: var(--coral);
}

.page-about .hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: clamp(28px, 5vw, 44px) 0 0;
  border-top: 1px solid var(--line);
  border-left: 1px solid var(--line);
}
.page-about .hero-stat {
  padding: 14px 16px 16px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--deep-800);
}
.page-about .hero-stat dt {
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--mist);
}
.page-about .hero-stat dd {
  margin: 8px 0 0;
  font-family: var(--font-mono);
  font-size: 24px;
  line-height: 1;
  color: var(--ink);
  font-variant-numeric: tabular-nums;
}

.page-about .hero-media {
  margin: clamp(28px, 5vw, 52px) 0 0;
}
.page-about .hero-media .media-frame {
  position: relative;
  aspect-ratio: 2 / 1;
  border: 1px solid var(--line);
  background: var(--deep-800);
}
.page-about .media-frame img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}
.page-about .media-caption {
  margin: 10px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist);
}

/* 章节骨架 */
.page-about .chapter {
  padding: clamp(36px, 6vw, 76px) 0;
  border-top: 1px solid var(--line-soft);
}
.page-about .chapter-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(18px, 3.4vw, 36px);
}
.page-about .chapter-rail {
  display: flex;
  align-items: baseline;
  gap: 12px;
}
.page-about .chapter-big {
  font-family: var(--font-mono);
  font-size: clamp(34px, 5vw, 62px);
  line-height: 1;
  letter-spacing: 0.01em;
  color: var(--coral);
  font-variant-numeric: tabular-nums;
}
.page-about .rail-label {
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--mist);
}

.page-about .chapter-body h2 {
  margin: 10px 0 0;
  max-width: 26ch;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: clamp(24px, 3.4vw, 38px);
  line-height: 1.2;
  letter-spacing: -0.015em;
  color: var(--ink);
}
.page-about .chapter-body > p {
  margin: 16px 0 0;
  max-width: 62ch;
  font-size: 17px;
  line-height: 1.75;
  color: var(--mist);
}
.page-about .chapter-body .note {
  margin-top: 20px;
  max-width: 60ch;
  padding-left: 14px;
  border-left: 2px solid var(--line);
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}
.page-about .chapter-body .note--gold {
  border-left-color: var(--gold);
}
.page-about .chapter-body .note a {
  color: var(--coral);
  text-decoration: none;
  border-bottom: 1px solid currentColor;
}
.page-about .chapter-body .note a:hover,
.page-about .chapter-body .note a:focus-visible {
  color: var(--cyan);
}

/* 六大区域地图 */
.page-about .region-map {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 28px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
  border-left: 1px solid var(--line);
}
.page-about .region-cell {
  position: relative;
  padding: 18px 16px 22px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background-color: var(--deep-800);
  background-image:
    linear-gradient(to right, var(--grid-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid-line) 1px, transparent 1px);
  background-size: 18px 18px;
  transition: background-color 0.35s var(--ease), border-color 0.35s var(--ease);
}
.page-about .region-cell:hover {
  background-color: var(--deep-700);
  border-color: var(--cyan);
}
.page-about .region-name {
  display: block;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 20px;
  letter-spacing: 0.02em;
  color: var(--ink);
}
.page-about .region-count {
  display: block;
  margin-top: 14px;
  font-family: var(--font-mono);
  font-size: 30px;
  line-height: 1;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}
.page-about .region-unit {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mist);
}
.page-about .region-cities {
  display: block;
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  line-height: 1.65;
  color: var(--mist);
}

/* 时间轴 */
.page-about .timeline-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 40px);
  margin-top: 28px;
}
.page-about .timeline-figure {
  margin: 0;
}
.page-about .timeline-figure .media-frame {
  aspect-ratio: 9 / 13;
  border: 1px solid var(--line);
  background: var(--deep-800);
}
.page-about .timeline {
  position: relative;
  margin: 0;
  padding: 4px 0 4px 26px;
  list-style: none;
}
.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: var(--cyan);
  opacity: 0.85;
}
.page-about .tl-node {
  position: relative;
  padding-bottom: 28px;
}
.page-about .tl-node:last-child {
  padding-bottom: 0;
}
.page-about .tl-node::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 7px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--gold);
  box-shadow: 0 0 0 3px rgba(245, 185, 66, 0.18);
}
.page-about .tl-phase {
  display: block;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.01em;
  color: var(--ink);
}
.page-about .tl-summary {
  margin: 8px 0 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}
.page-about .tl-more {
  margin-top: 10px;
}
.page-about .tl-more summary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  list-style: none;
  cursor: pointer;
  font-size: 14px;
  letter-spacing: 0.02em;
  color: var(--coral);
}
.page-about .tl-more summary::-webkit-details-marker {
  display: none;
}
.page-about .tl-more summary::before {
  content: "+";
  font-family: var(--font-mono);
  font-size: 15px;
  line-height: 1;
  color: var(--coral);
}
.page-about .tl-more[open] summary::before {
  content: "\2013";
}
.page-about .tl-more summary:hover,
.page-about .tl-more summary:focus-visible {
  color: var(--cyan);
}
.page-about .tl-more summary:hover::before,
.page-about .tl-more summary:focus-visible::before {
  color: var(--cyan);
}
.page-about .tl-more p {
  margin: 10px 0 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

/* 档案四类内容 */
.page-about .dossier-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  margin: 28px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
  border-left: 1px solid var(--line);
}
.page-about .dossier-item {
  padding: 20px 18px 24px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--deep-800);
  transition: background-color 0.3s var(--ease), border-color 0.3s var(--ease);
}
.page-about .dossier-item:hover {
  background: var(--deep-700);
  border-color: var(--cyan);
}
.page-about .dossier-no {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.16em;
  color: var(--cyan);
}
.page-about .dossier-item h3 {
  margin: 10px 0 0;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 19px;
  color: var(--ink);
}
.page-about .dossier-item p {
  margin: 10px 0 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

/* 团队与节奏 */
.page-about .team-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 32px);
  margin-top: 28px;
}
.page-about .team-stats {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}
.page-about .team-stats li {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding: 14px 2px;
  border-bottom: 1px solid var(--line);
}
.page-about .team-stats .num {
  flex: 0 0 auto;
  min-width: 3.4ch;
  font-family: var(--font-mono);
  font-size: 26px;
  line-height: 1;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}
.page-about .team-stats li span:last-child {
  font-size: 15px;
  line-height: 1.65;
  color: var(--mist);
}
.page-about .team-figure {
  margin: 0;
}
.page-about .team-figure .media-frame {
  aspect-ratio: 10 / 7;
  border: 1px solid var(--line);
  background: var(--deep-800);
}

/* 继续深入入口 */
.page-about .entry-links {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  margin-top: 26px;
  border-top: 1px solid var(--line);
  border-left: 1px solid var(--line);
}
.page-about .entry-link {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 20px 18px 22px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--deep-800);
  text-decoration: none;
  color: var(--ink);
  transition: background-color 0.3s var(--ease), border-color 0.3s var(--ease);
}
.page-about .entry-link:hover,
.page-about .entry-link:focus-visible {
  background: var(--deep-700);
  border-color: var(--cyan);
}
.page-about .entry-link em {
  font-style: normal;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--coral);
}
.page-about .entry-link strong {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.01em;
}
.page-about .entry-link span {
  font-size: 15px;
  line-height: 1.7;
  color: var(--mist);
}

/* 中屏 */
@media (min-width: 640px) {
  .page-about .timeline-wrap {
    grid-template-columns: minmax(0, 1fr);
  }
  .page-about .entry-links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .dossier-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .hero-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .region-map {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

/* 大屏 */
@media (min-width: 900px) {
  .page-about .chapter-grid {
    grid-template-columns: minmax(150px, 0.62fr) minmax(0, 2fr);
    gap: clamp(32px, 5vw, 72px);
  }
  .page-about .chapter-rail {
    position: sticky;
    top: var(--about-rail-top);
    align-self: start;
    flex-direction: column;
    gap: 10px;
  }
  .page-about .region-map {
    grid-template-columns: repeat(6, minmax(0, 1fr));
  }
  .page-about .team-layout {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    align-items: start;
  }
}

@media (min-width: 1040px) {
  .page-about .timeline-wrap {
    grid-template-columns: 280px minmax(0, 1fr);
    align-items: start;
  }
}

/* 降低动态效果 */
@media (prefers-reduced-motion: reduce) {
  .page-about .region-cell,
  .page-about .dossier-item,
  .page-about .entry-link,
  .page-about .breadcrumb-item a {
    transition: none;
  }
}
</main>