.page-about {
  --about-rule: rgba(232, 224, 206, .16);
  --about-body-text: #C9D5CE;
  --about-sand-ink: #3E4E45;
  --about-sand-dim: #5A6B60;
  --about-deep-hover: #102A22;
  --about-rail-w: 208px;
  position: relative;
  background: var(--bb-night);
  color: var(--bb-mist);
}

.page-about::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: .5;
  background-image:
    linear-gradient(to right, rgba(30, 58, 49, .55) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(30, 58, 49, .38) 1px, transparent 1px);
  background-size: 96px 96px;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  z-index: 1;
  padding-top: clamp(38px, 7vw, 84px);
  padding-bottom: clamp(30px, 5vw, 56px);
}

.page-about .about-hero .breadcrumb {
  margin-bottom: clamp(22px, 3.4vw, 36px);
}

.page-about .about-eyebrow {
  display: block;
  margin: 0 0 14px;
}

.page-about .about-title {
  font-family: var(--bb-font-display);
  font-weight: 300;
  font-size: clamp(36px, 7.4vw, 72px);
  line-height: 1.06;
  letter-spacing: -0.02em;
  color: var(--bb-mist);
  margin: 0 0 clamp(18px, 2.6vw, 26px);
  max-width: 16ch;
}

.page-about .about-lede {
  margin: 0;
  max-width: 66ch;
  font-family: var(--bb-font-body);
  font-size: clamp(16px, 1.7vw, 18px);
  line-height: 1.8;
  color: var(--bb-sage);
}

.page-about .about-stats {
  list-style: none;
  margin: clamp(28px, 4.5vw, 46px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--bb-line);
  border: 1px solid var(--bb-line);
  border-radius: var(--bb-radius);
  overflow: hidden;
}

.page-about .about-stat {
  background: var(--bb-deep);
  padding: clamp(16px, 2.4vw, 24px) clamp(16px, 2.4vw, 26px);
  transition: background 160ms var(--bb-ease);
}

.page-about .about-stat:hover {
  background: var(--about-deep-hover);
}

.page-about .stat-num {
  display: block;
  font-family: var(--bb-font-mono);
  font-variant-numeric: tabular-nums;
  font-weight: 500;
  font-size: clamp(26px, 3.6vw, 34px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--bb-lime);
  white-space: nowrap;
}

.page-about .stat-label {
  display: block;
  margin-top: 10px;
  font-family: var(--bb-font-display);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--bb-sage);
}

/* ---------- 主体骨架 ---------- */
.page-about .about-body {
  position: relative;
  z-index: 1;
  padding-bottom: clamp(56px, 8vw, 104px);
}

.page-about .about-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 5vw, 40px);
}

/* ---------- 纵向索引 ---------- */
.page-about .about-rail {
  border-top: 1px solid var(--bb-line);
  border-bottom: 1px solid var(--bb-line);
  padding: 16px 0 14px;
}

.page-about .about-rail-title {
  display: block;
  margin: 0 0 12px;
}

.page-about .about-timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 4px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-timeline::-webkit-scrollbar {
  display: none;
}

.page-about .about-timeline li {
  flex: 0 0 auto;
}

.page-about .about-timeline a {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding: 8px 14px;
  border: 1px solid var(--bb-line);
  border-radius: 999px;
  text-decoration: none;
  color: var(--bb-mist);
  font-size: 13px;
  white-space: nowrap;
  transition: border-color 160ms var(--bb-ease), color 160ms var(--bb-ease);
}

.page-about .about-timeline a:hover,
.page-about .about-timeline a:focus-visible {
  border-color: var(--bb-lime);
  color: var(--bb-lime);
}

.page-about .tl-year {
  font-family: var(--bb-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--bb-lime);
  white-space: nowrap;
}

.page-about .tl-name {
  color: currentColor;
}

/* ---------- 章节 ---------- */
.page-about .about-section {
  padding-bottom: clamp(34px, 5vw, 60px);
  border-bottom: 1px solid var(--about-rule);
}

.page-about .about-section + .about-section {
  padding-top: clamp(34px, 5vw, 60px);
}

.page-about .about-section:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .about-section h2 {
  font-family: var(--bb-font-display);
  font-weight: 300;
  font-size: clamp(26px, 3.6vw, 38px);
  line-height: 1.16;
  letter-spacing: -0.01em;
  color: var(--bb-mist);
  margin: 10px 0 clamp(16px, 2.4vw, 24px);
  max-width: 22ch;
}

.page-about .about-section > p {
  margin: 0 0 1.05em;
  max-width: 68ch;
  font-size: clamp(16px, 1.6vw, 17px);
  line-height: 1.8;
  color: var(--about-body-text);
}

.page-about .about-section > p:last-child {
  margin-bottom: 0;
}

.page-about .about-inline-link {
  margin-top: clamp(16px, 2.4vw, 22px);
}

.page-about .about-inline-link a {
  font-size: 15px;
  color: var(--bb-lime);
}

/* ---------- 沙色数字卡 ---------- */
.page-about .sand-card {
  position: relative;
  background: var(--bb-sand);
  color: var(--bb-deep);
  border-radius: var(--bb-radius);
  padding: clamp(20px, 2.8vw, 30px) clamp(20px, 3vw, 32px);
  margin: clamp(24px, 3.6vw, 36px) 0 0;
  box-shadow: 0 20px 44px rgba(0, 0, 0, .3);
  transition: transform 180ms var(--bb-ease), box-shadow 180ms var(--bb-ease);
}

.page-about .sand-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 28px 56px rgba(0, 0, 0, .38);
}

.page-about .sand-card:focus-visible {
  outline: 2px solid var(--bb-lime);
  outline-offset: 3px;
}

.page-about .card-num {
  display: block;
  font-family: var(--bb-font-mono);
  font-variant-numeric: tabular-nums;
  font-weight: 500;
  font-size: clamp(28px, 4.4vw, 44px);
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--bb-deep);
  white-space: nowrap;
}

.page-about .card-label {
  display: block;
  margin-top: 10px;
  font-family: var(--bb-font-display);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--about-sand-dim);
}

.page-about .card-hint {
  margin: 14px 0 0;
  padding-top: 12px;
  border-top: 1px solid rgba(14, 36, 30, .16);
  font-size: 14px;
  line-height: 1.68;
  color: var(--about-sand-ink);
}

.page-about .sand-card p.card-hint {
  max-width: none;
  font-size: 14px;
}

/* ---------- 图 ---------- */
.page-about .about-figure {
  margin: clamp(24px, 3.6vw, 38px) 0 0;
}

.page-about .about-figure .media-frame {
  border-radius: var(--bb-radius);
  overflow: hidden;
  border: 1px solid var(--bb-line);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.page-about .about-figure .media-caption {
  display: block;
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--bb-sage);
  max-width: 60ch;
}

.page-about .about-figure--portrait {
  max-width: 380px;
}

/* ---------- 行动按钮 ---------- */
.page-about .about-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(24px, 3.6vw, 34px);
}

/* ---------- 桌面：左右分栏 + 贴滚动索引 ---------- */
@media (min-width: 960px) {
  .page-about .about-grid {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(40px, 4.6vw, 80px);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 104px;
    border-top: 0;
    border-bottom: 0;
    border-left: 1px solid var(--bb-line);
    padding: 0 0 0 22px;
  }

  .page-about .about-rail-title {
    margin: 0 0 14px;
  }

  .page-about .about-timeline {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about .about-timeline li {
    position: relative;
  }

  .page-about .about-timeline li::before {
    content: "";
    position: absolute;
    left: -26px;
    top: 19px;
    width: 7px;
    height: 7px;
    border-radius: 50%;
    background: var(--bb-line);
    transition: background 160ms var(--bb-ease), box-shadow 160ms var(--bb-ease);
  }

  .page-about .about-timeline li:hover::before {
    background: var(--bb-lime);
    box-shadow: 0 0 0 4px rgba(184, 255, 60, .14);
  }

  .page-about .about-timeline a {
    display: flex;
    width: 100%;
    padding: 13px 0;
    border: 0;
    border-bottom: 1px solid var(--bb-line);
    border-radius: 0;
    color: var(--bb-sage);
    font-size: 14px;
  }

  .page-about .about-timeline li:first-child a {
    border-top: 1px solid var(--bb-line);
  }

  .page-about .about-timeline a:hover,
  .page-about .about-timeline a:focus-visible {
    color: var(--bb-mist);
  }

  .page-about .sand-card {
    max-width: 66%;
  }

  .page-about .sand-card--right {
    margin-left: auto;
  }
}

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

  .page-about .about-figure--right {
    margin-left: auto;
    max-width: 82%;
  }
}

/* ---------- 悬停展开字段说明 ---------- */
@media (hover: hover) and (pointer: fine) {
  .page-about .card-hint {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    margin-top: 0;
    padding-top: 0;
    border-top-color: transparent;
    transition: max-height 200ms var(--bb-ease),
                opacity 180ms var(--bb-ease),
                margin-top 200ms var(--bb-ease),
                padding-top 200ms var(--bb-ease);
  }

  .page-about .sand-card:hover .card-hint,
  .page-about .sand-card:focus .card-hint {
    max-height: 220px;
    opacity: 1;
    margin-top: 14px;
    padding-top: 12px;
    border-top-color: rgba(14, 36, 30, .16);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .sand-card,
  .page-about .about-timeline a,
  .page-about .about-stat,
  .page-about .card-hint {
    transition: none;
  }

  .page-about .sand-card:hover {
    transform: none;
  }
}