.page-about {
  --about-rail: 208px;
}

/* ============ 页面题头 ============ */
.page-about .about-hero {
  padding: 28px 0 20px;
}

.page-about .about-hero-grid {
  display: grid;
  gap: 30px;
}

.page-about .about-title {
  margin-top: 12px;
  max-width: 17ch;
}

.page-about .about-lead {
  margin-top: 16px;
  max-width: 46ch;
  color: var(--text-dim);
}

.page-about .about-hero-facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  border-top: 1px solid var(--rule);
  padding-top: 18px;
}

.page-about .about-fact {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 0;
}

.page-about .about-fact-k {
  font-family: var(--font-mono);
  font-size: 24px;
  font-weight: 700;
  line-height: 1;
  color: var(--text);
  padding-bottom: 8px;
  border-bottom: 2px solid var(--violet);
}

.page-about .about-fact-l {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--text-dim);
}

/* ============ 主体布局：侧边章节索引 + 纵向叙述 ============ */
.page-about .about-layout {
  display: grid;
  gap: 32px;
  padding-bottom: 64px;
}

.page-about .about-rail {
  border-top: 1px solid var(--rule);
  padding-top: 12px;
}

.page-about .about-rail .toc-title {
  display: none;
}

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

.page-about .about-rail .toc-link {
  display: block;
  white-space: nowrap;
  padding: 6px 12px;
  font-size: 13px;
  color: var(--text-dim);
  text-decoration: none;
  border: 1px solid var(--rule);
  border-radius: 999px;
  transition: color 180ms var(--ease), border-color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .about-rail .toc-link:hover {
  color: var(--text);
  border-color: var(--rule-strong);
}

.page-about .about-rail .toc-link.is-active,
.page-about .about-rail .toc-link[aria-current] {
  color: var(--text);
  border-color: var(--violet);
  background: rgba(124, 58, 237, 0.2);
}

.page-about .about-flow {
  display: flex;
  flex-direction: column;
  gap: 68px;
  min-width: 0;
}

/* ============ 区块通用 ============ */
.page-about .about-section {
  scroll-margin-top: 124px;
  min-width: 0;
}

.page-about .about-section .section-head {
  margin-bottom: 22px;
}

.page-about .about-section .section-title {
  margin-top: 8px;
}

.page-about .about-section .section-note {
  margin-top: 10px;
  max-width: 52ch;
  color: var(--text-dim);
}

.page-about .about-prose {
  max-width: 40em;
}

.page-about .about-prose p + p {
  margin-top: 16px;
}

/* ============ 起点说明牌 ============ */
.page-about .about-plate {
  margin-top: 30px;
  max-width: 54ch;
  padding: 8px 0 8px 18px;
  border-left: 3px solid var(--orange);
  background: linear-gradient(90deg, rgba(255, 122, 26, 0.12), transparent 78%);
}

.page-about .about-plate-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--sign);
  border: 1px solid rgba(255, 231, 194, 0.42);
  border-radius: 3px;
  padding: 3px 8px;
}

.page-about .about-plate p {
  margin: 12px 0 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
}

/* ============ 版本时间轴 ============ */
.page-about .about-timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 32px;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--blue) 0%, var(--violet) 54%, var(--orange) 100%);
  opacity: 0.9;
}

.page-about .about-node {
  position: relative;
  min-width: 0;
}

.page-about .about-node::before {
  content: "";
  position: absolute;
  left: -32px;
  top: 7px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--ink);
  border: 2px solid var(--blue);
  box-shadow: 0 0 0 4px rgba(29, 107, 255, 0.14);
  transition: border-color 200ms var(--ease), box-shadow 200ms var(--ease);
}

.page-about .about-node:hover::before {
  border-color: var(--orange);
  box-shadow: 0 0 0 5px rgba(255, 122, 26, 0.2);
}

.page-about .about-node-title {
  margin: 0;
  font-size: 18px;
  font-weight: 800;
  line-height: 1.5;
  color: var(--text);
}

.page-about .about-year {
  display: inline-block;
  margin-right: 10px;
  padding: 2px 8px;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--orange);
  border: 1px solid rgba(255, 122, 26, 0.42);
  border-radius: 3px;
  vertical-align: 2px;
}

.page-about .about-node-text {
  margin: 8px 0 0;
  max-width: 48em;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--text-dim);
}

/* ============ 图片 ============ */
.page-about .about-figure {
  margin: 34px 0 0;
  max-width: 100%;
}

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

.page-about .about-figure .media-caption {
  margin-top: 10px;
  font-size: 13px;
  letter-spacing: 0.02em;
  color: var(--text-dim);
}

/* ============ 版本叠层对比 ============ */
.page-about .about-version-pair {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-top: 34px;
}

.page-about .about-sheet {
  padding: 18px 20px;
  border: 1px solid var(--rule-strong);
  border-radius: 4px;
  background: var(--panel);
  min-width: 0;
}

.page-about .about-sheet--under {
  border-style: dashed;
  background: rgba(22, 20, 58, 0.72);
}

.page-about .about-sheet--over {
  background:
    linear-gradient(145deg, rgba(124, 58, 237, 0.24), rgba(10, 9, 24, 0.92) 64%),
    var(--panel);
  border-color: rgba(124, 58, 237, 0.5);
}

.page-about .about-sheet-title {
  margin: 12px 0 8px;
  font-size: 17px;
  font-weight: 800;
  color: var(--text);
}

.page-about .about-sheet-text {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
}

/* ============ 栏目分组展板 ============ */
.page-about .about-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0 0 20px;
}

.page-about .about-board {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(132px, 1fr));
  gap: 10px;
  padding: 20px;
  border: 1px solid var(--rule);
  border-radius: 6px;
  background-image:
    repeating-linear-gradient(0deg, rgba(29, 107, 255, 0.08) 0 1px, transparent 1px 26px),
    repeating-linear-gradient(90deg, rgba(29, 107, 255, 0.08) 0 1px, transparent 1px 26px),
    linear-gradient(158deg, rgba(29, 107, 255, 0.12), rgba(124, 58, 237, 0.06) 62%, transparent);
}

.page-about .about-col {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 62px;
  padding: 10px 8px;
  text-align: center;
  font-size: 13.5px;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--ink-on-paper);
  background: var(--sign);
  border: 1px solid rgba(26, 24, 54, 0.2);
  border-radius: 3px;
  transition: transform 180ms var(--ease), box-shadow 180ms var(--ease);
}

.page-about .about-col[hidden] {
  display: none;
}

.page-about .about-col:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 22px rgba(10, 9, 24, 0.5);
}

.page-about .about-board-note {
  margin: 16px 0 0;
  max-width: 52ch;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--text-dim);
}

/* ============ 班次表与提示 ============ */
.page-about .about-table-wrap {
  margin-top: 24px;
}

.page-about .about-callout {
  margin-top: 26px;
  max-width: 60ch;
}

.page-about .about-callout p {
  margin: 0;
  line-height: 1.82;
}

/* ============ 团队数字块 ============ */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(132px, 1fr));
  gap: 14px;
  margin: 26px 0;
}

.page-about .about-stat {
  padding: 12px 14px 14px;
  border-left: 2px solid var(--violet);
  border-radius: 0 4px 4px 0;
  background: linear-gradient(90deg, rgba(124, 58, 237, 0.16), transparent 80%);
}

.page-about .about-stat-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 28px;
  font-weight: 700;
  line-height: 1.1;
  color: var(--text);
}

.page-about .about-stat-cap {
  display: block;
  margin-top: 6px;
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--text-dim);
}

/* ============ 属性清单 ============ */
.page-about .about-attr-list {
  margin: 24px 0 0;
  padding: 0;
  border-top: 1px solid var(--rule);
}

.page-about .about-attr {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 16px;
  padding: 12px 2px;
  border-bottom: 1px solid var(--rule);
}

.page-about .about-attr dt {
  flex: 0 0 auto;
  min-width: 6.5em;
  padding-top: 2px;
  font-size: 12.5px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--text-dim);
}

.page-about .about-attr dd {
  flex: 1 1 12em;
  margin: 0;
  font-size: 15.5px;
  color: var(--text);
}

.page-about .about-contact-strip {
  margin-top: 26px;
  padding: 18px 20px;
  border: 1px solid var(--rule);
  border-left: 3px solid var(--cyan);
  border-radius: 0 4px 4px 0;
  background: linear-gradient(120deg, rgba(47, 230, 200, 0.08), transparent 70%);
}

.page-about .about-contact-strip p {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.82;
  color: var(--text-dim);
}

.page-about .about-actions {
  margin-top: 28px;
}

/* ============ 桌面端 ============ */
@media (min-width: 900px) {
  .page-about .about-hero {
    padding: 48px 0 30px;
  }

  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 1.4fr) minmax(0, 0.6fr);
    align-items: end;
    gap: 48px;
  }

  .page-about .about-hero-facts {
    border-top: 0;
    border-left: 1px solid var(--rule);
    padding-top: 0;
    padding-left: 26px;
    grid-template-columns: minmax(0, 1fr);
    gap: 18px;
  }

  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 46px;
    align-items: start;
    padding-bottom: 96px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 132px;
    border-top: 0;
    border-left: 1px solid var(--rule);
    padding: 0 0 0 16px;
  }

  .page-about .about-rail .toc-title {
    display: block;
    margin: 0 0 12px;
    font-size: 12px;
    font-weight: 600;
    letter-spacing: 0.1em;
    color: var(--text-dim);
  }

  .page-about .about-rail .toc-list {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about .about-rail .toc-link {
    padding: 7px 0 7px 12px;
    margin-left: -2px;
    font-size: 14px;
    border: 0;
    border-left: 2px solid transparent;
    border-radius: 0;
    background: none;
  }

  .page-about .about-rail .toc-link:hover {
    color: var(--text);
    border-left-color: var(--rule-strong);
  }

  .page-about .about-rail .toc-link.is-active,
  .page-about .about-rail .toc-link[aria-current] {
    color: var(--text);
    border-left-color: var(--magenta);
    background: none;
  }

  .page-about .about-flow {
    gap: 88px;
  }

  .page-about .about-timeline {
    padding-left: 40px;
  }

  .page-about .about-timeline::before {
    left: 6px;
  }

  .page-about .about-node::before {
    left: -40px;
  }

  .page-about .about-version-pair {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
    padding: 0 30px 30px 0;
  }

  .page-about .about-sheet--under {
    grid-area: 1 / 1;
    transform: translate(30px, 30px);
    z-index: 0;
  }

  .page-about .about-sheet--over {
    grid-area: 1 / 1;
    z-index: 1;
    transition: transform 260ms var(--ease), box-shadow 260ms var(--ease);
  }
}

@media (min-width: 900px) and (hover: hover) {
  .page-about .about-version-pair:hover .about-sheet--over {
    transform: translate(-10px, -10px);
    box-shadow: 0 20px 44px rgba(10, 9, 24, 0.58);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-col:hover,
  .page-about .about-node::before,
  .page-about .about-sheet--over {
    transition: none;
  }

  .page-about .about-version-pair:hover .about-sheet--over {
    transform: none;
  }

  .page-about .about-col:hover {
    transform: none;
  }
}