.page-about {
  --about-rail: 172px;
  --about-axis: 48px;
  --about-night-line: rgba(244, 239, 228, 0.22);
}

/* ---------- 首屏 ---------- */
.page-about .about-mast {
  padding-top: calc(var(--header-h) + clamp(28px, 7vw, 88px));
  background: var(--paper);
}

.page-about .mast-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--sp-3);
  padding-bottom: clamp(36px, 7vw, 88px);
}

.page-about .mast-index {
  color: var(--line);
  margin: 0;
}

.page-about .mast-title {
  margin: 0;
  color: var(--ink);
}

.page-about .mast-lead {
  margin: 0;
  color: var(--ink-body);
  font-size: clamp(16px, 1.6vw, 19px);
  line-height: 1.85;
}

.page-about .mast-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-4);
  padding-top: var(--sp-2);
  border-top: 1px solid var(--line-soft);
}

.page-about .mast-meta .label-mono {
  color: var(--sea);
}

.page-about .about-mast .angle-band {
  height: clamp(28px, 5vw, 56px);
}

@media (min-width: 900px) {
  .page-about .mast-grid {
    grid-template-columns: repeat(12, minmax(0, 1fr));
    column-gap: var(--sp-3);
  }

  .page-about .mast-index {
    grid-column: 1 / 13;
  }

  .page-about .mast-title {
    grid-column: 1 / 10;
  }

  .page-about .mast-lead {
    grid-column: 7 / 13;
  }

  .page-about .mast-meta {
    grid-column: 1 / 7;
  }
}

/* ---------- 纵向时间轴 ---------- */
.page-about .track-section {
  background: var(--paper);
}

.page-about .track {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
}

.page-about .track-rail {
  display: none;
}

@media (min-width: 900px) {
  .page-about .track {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: var(--sp-5);
  }

  .page-about .track-rail {
    display: block;
    grid-column: 1;
    grid-row: 1 / -1;
    align-self: start;
    position: sticky;
    top: calc(var(--header-h) + 28px);
  }

  .page-about .track > *:not(.track-rail) {
    grid-column: 2;
  }
}

.page-about .rail-inner {
  border-top: 1px solid var(--line);
  padding-top: var(--sp-2);
}

.page-about .rail-label {
  color: var(--line);
  margin: 0 0 var(--sp-3);
}

.page-about .rail-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .rail-link {
  display: flex;
  align-items: baseline;
  gap: var(--sp-1);
  padding: 6px 0;
  color: var(--ink-body);
  text-decoration: none;
  font-size: 14px;
  border-bottom: 1px solid transparent;
  transition: color 240ms var(--ease), border-color 240ms var(--ease);
}

.page-about .rail-link:hover,
.page-about .rail-link:focus-visible {
  color: var(--ink);
  border-bottom-color: var(--amber);
}

.page-about .rail-num {
  font-size: 11px;
  color: var(--amber);
  letter-spacing: .12em;
}

.page-about .rail-name {
  letter-spacing: .02em;
}

/* 节点 */
.page-about .tl-node {
  position: relative;
  padding-left: var(--about-axis);
  padding-bottom: clamp(40px, 6vw, 72px);
}

.page-about .tl-node::before {
  content: "";
  position: absolute;
  left: 13px;
  top: 10px;
  bottom: -6px;
  width: 1px;
  background: var(--line-soft);
}

.page-about .tl-node::after {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  width: 13px;
  height: 13px;
  background: var(--amber);
}

.page-about .tl-node:last-child::before {
  bottom: auto;
  height: 56px;
}

.page-about .tl-tag {
  color: var(--sea);
  margin: 0 0 var(--sp-2);
}

.page-about .tl-title {
  margin: 0 0 var(--sp-3);
  color: var(--ink);
  font-size: clamp(24px, 3.4vw, 38px);
}

.page-about .tl-node .prose {
  margin: 0 0 var(--sp-3);
}

.page-about .tl-node .prose:last-child {
  margin-bottom: 0;
}

/* 小节数据 */
.page-about .mini-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 0;
  margin-top: var(--sp-3);
  border-top: 1px solid var(--line-soft);
}

.page-about .mini-stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: var(--sp-3) var(--sp-2) var(--sp-3) 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .mini-num {
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1;
  color: var(--ink);
}

.page-about .mini-num--sea {
  color: var(--sea);
}

.page-about .mini-stat .label-mono {
  color: var(--line);
}

/* ---------- 收藏横切带 ---------- */
.page-about .collect-band {
  background: var(--night);
  color: var(--on-night-strong);
  padding: clamp(32px, 5vw, 64px) clamp(20px, 4vw, 48px);
  margin-bottom: clamp(40px, 6vw, 72px);
}

.page-about .collect-kicker {
  color: var(--amber);
  margin: 0 0 var(--sp-2);
}

.page-about .collect-title {
  margin: 0 0 var(--sp-3);
  color: var(--on-night-strong);
  font-size: clamp(24px, 3.4vw, 38px);
  max-width: 20em;
}

.page-about .collect-lead {
  margin: 0;
  color: var(--on-night);
  font-size: clamp(15px, 1.5vw, 18px);
  line-height: 1.85;
  max-width: 46em;
}

.page-about .collect-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--sp-4);
  margin-top: clamp(28px, 4vw, 48px);
}

.page-about .collect-figure {
  margin: 0;
}

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

.page-about .collect-band .figure-caption {
  color: var(--on-night);
  margin-top: var(--sp-2);
}

.page-about .collect-cards {
  display: grid;
  gap: var(--sp-3);
}

.page-about .collect-card {
  border-top: 1px solid var(--about-night-line);
  padding-top: var(--sp-3);
}

.page-about .collect-icon {
  display: block;
  margin-bottom: var(--sp-2);
  color: var(--sea-mist);
  transition: color 240ms var(--ease);
}

.page-about .collect-icon svg {
  display: block;
  stroke-width: 1.5;
  transition: stroke-width 240ms var(--ease);
}

.page-about .collect-card:hover .collect-icon,
.page-about .collect-card:focus-within .collect-icon {
  color: var(--amber);
}

.page-about .collect-card:hover .collect-icon svg,
.page-about .collect-card:focus-within .collect-icon svg {
  stroke-width: 2.4;
}

.page-about .collect-name {
  margin: 0 0 var(--sp-1);
  color: var(--on-night-strong);
  font-size: clamp(18px, 2vw, 22px);
}

.page-about .collect-text {
  margin: 0;
  color: var(--on-night);
  font-size: 15px;
  line-height: 1.8;
}

@media (min-width: 760px) {
  .page-about .collect-layout {
    grid-template-columns: repeat(12, minmax(0, 1fr));
    column-gap: var(--sp-3);
  }

  .page-about .collect-figure {
    grid-column: 1 / 6;
  }

  .page-about .collect-cards {
    grid-column: 7 / 13;
  }

  .page-about .collect-figure--offset {
    grid-column: 8 / 13;
    margin-top: var(--sp-4);
  }
}

/* ---------- 团队 ---------- */
.page-about .team-figure {
  margin: var(--sp-4) 0 0;
}

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

.page-about .team-figure .figure-caption {
  color: var(--line);
  margin-top: var(--sp-2);
}

.page-about .fold-list {
  margin-top: var(--sp-4);
  border-top: 1px solid var(--line);
}

.page-about .fold-item {
  border-bottom: 1px solid var(--line-soft);
}

.page-about .fold-summary {
  display: flex;
  align-items: baseline;
  gap: var(--sp-2);
  padding: var(--sp-3) 0;
  cursor: pointer;
  list-style: none;
}

.page-about .fold-summary::-webkit-details-marker {
  display: none;
}

.page-about .fold-key {
  font-size: 12px;
  color: var(--amber);
  letter-spacing: .16em;
}

.page-about .fold-name {
  font-size: 17px;
  color: var(--ink);
}

.page-about .fold-hint {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--line);
}

.page-about .fold-hint::before {
  content: "展开";
}

.page-about .fold-item[open] .fold-hint::before {
  content: "收起";
}

.page-about .fold-body {
  padding: 0 0 var(--sp-3);
  max-width: 46em;
}

.page-about .fold-body p {
  margin: 0;
  color: var(--ink-body);
  font-size: 16px;
  line-height: 1.85;
}

/* ---------- 里程碑 ---------- */
.page-about .milestones {
  list-style: none;
  margin: var(--sp-3) 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.page-about .milestone {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: var(--sp-2);
  align-items: baseline;
  padding: var(--sp-3) 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .ms-num {
  font-size: 13px;
  color: var(--sea);
  letter-spacing: .12em;
}

.page-about .ms-text {
  color: var(--ink-body);
  font-size: 16px;
  line-height: 1.75;
}

/* ---------- 收尾 ---------- */
.page-about .about-next {
  border-top: 1px solid var(--line);
  padding: clamp(40px, 6vw, 72px) 0 clamp(56px, 8vw, 96px);
  background: var(--paper);
}

.page-about .next-heading {
  margin: 0 0 var(--sp-4);
  color: var(--ink);
  font-size: clamp(22px, 2.6vw, 30px);
}

.page-about .next-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .next-list li {
  border-bottom: 1px solid var(--line-soft);
}

.page-about .next-list a {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--sp-1) var(--sp-3);
  padding: var(--sp-3) 0;
  color: var(--ink);
  text-decoration: none;
  font-size: 17px;
  transition: color 240ms var(--ease), padding-left 240ms var(--ease);
}

.page-about .next-list a:hover,
.page-about .next-list a:focus-visible {
  color: var(--sea);
  padding-left: var(--sp-2);
}

.page-about .next-list .label-mono {
  color: var(--line);
}

/* ---------- 窄屏保护 ---------- */
@media (max-width: 480px) {
  .page-about .tl-node {
    padding-left: 32px;
  }

  .page-about .tl-node::before {
    left: 9px;
  }

  .page-about .tl-node::after {
    left: 3px;
  }

  .page-about .milestone {
    grid-template-columns: 34px minmax(0, 1fr);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .rail-link,
  .page-about .collect-icon,
  .page-about .collect-icon svg,
  .page-about .next-list a {
    transition: none;
  }

  .page-about .next-list a:hover,
  .page-about .next-list a:focus-visible {
    padding-left: 0;
  }
}