.page-about {
  --rail-w: 36px;
  --about-cut: 18px;
  position: relative;
  background: var(--ink-900);
  color: var(--text-primary);
  overflow-x: clip;
}

@media (min-width: 960px) {
  .page-about {
    --rail-w: 56px;
  }
}

/* ---------- 页首 ---------- */

.page-about .about-hero {
  position: relative;
  isolation: isolate;
  padding-bottom: clamp(36px, 7vw, 72px);
  border-bottom: 1px solid var(--line-400);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background-image: repeating-linear-gradient(
    90deg,
    rgba(74, 95, 120, 0.16) 0 1px,
    transparent 1px 80px
  );
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.85), transparent 78%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.85), transparent 78%);
}

.page-about .breadcrumb {
  margin-bottom: clamp(24px, 4vw, 40px);
}

.page-about .hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 5vw, 56px);
}

@media (min-width: 900px) {
  .page-about .hero-grid {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 0.85fr);
    gap: clamp(32px, 5vw, 72px);
    align-items: start;
  }
}

.page-about .hero-title {
  margin: 14px 0 0;
  font-size: var(--f-3xl);
  line-height: 1.12;
  letter-spacing: -0.02em;
  max-width: 20ch;
}

.page-about .hero-lead {
  margin-top: 20px;
  max-width: 62ch;
  font-size: var(--f-sm);
  line-height: 1.85;
  color: var(--text-muted);
}

.page-about .hero-facts {
  display: flex;
  flex-wrap: wrap;
  gap: 18px 34px;
  margin-top: 30px;
  padding-top: 20px;
  border-top: 1px solid var(--line-400);
}

.page-about .hero-fact {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding-left: 12px;
  border-left: 2px solid var(--gold-600);
}

.page-about .hero-fact .k {
  font-family: var(--mono);
  font-size: var(--f-2xs);
  letter-spacing: 0.12em;
  color: var(--text-muted);
}

.page-about .hero-fact .v {
  font-family: var(--mono);
  font-size: var(--f-md);
  font-weight: 500;
  color: var(--gold-400);
  line-height: 1.2;
}

.page-about .hero-side {
  padding: clamp(20px, 3vw, 28px);
  background: var(--ink-800);
  border: 1px solid var(--line-400);
  clip-path: polygon(
    0 0,
    calc(100% - var(--about-cut)) 0,
    100% var(--about-cut),
    100% 100%,
    0 100%
  );
}

.page-about .hero-side-note {
  margin: 12px 0 0;
  font-size: var(--f-xs);
  line-height: 1.7;
  color: var(--text-muted);
}

.page-about .hero-side-list {
  display: grid;
  gap: 2px;
  margin-top: 18px;
}

.page-about .hero-side-link {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 11px 12px;
  text-decoration: none;
  color: var(--text-primary);
  font-size: var(--f-xs);
  line-height: 1.5;
  border-left: 2px solid var(--line-400);
  background: rgba(255, 255, 255, 0.02);
  transition: background 0.18s var(--ease), border-color 0.18s var(--ease), color 0.18s var(--ease);
}

.page-about .hero-side-link .tick {
  flex: 0 0 auto;
  font-family: var(--mono);
  font-size: var(--f-2xs);
  letter-spacing: 0.06em;
  color: var(--gold-400);
}

.page-about .hero-side-link:hover,
.page-about .hero-side-link:focus-visible {
  border-left-color: var(--vermilion-500);
  background: rgba(255, 106, 43, 0.1);
  color: var(--vermilion-500);
}

.page-about .hero-side-foot {
  margin: 18px 0 0;
  padding-top: 14px;
  border-top: 1px solid var(--line-400);
  font-size: var(--f-2xs);
  line-height: 1.7;
  letter-spacing: 0.04em;
  color: var(--text-muted);
}

/* ---------- 区块标题 ---------- */

.page-about .sec-head {
  margin-bottom: clamp(28px, 5vw, 48px);
}

.page-about .sec-head h2 {
  margin: 10px 0 0;
  font-size: var(--f-2xl);
  line-height: 1.15;
  letter-spacing: -0.02em;
}

.page-about .sec-note {
  margin: 12px 0 0;
  max-width: 64ch;
  font-size: var(--f-sm);
  line-height: 1.8;
  color: var(--text-muted);
}

/* ---------- 时间线 ---------- */

.page-about .about-timeline {
  position: relative;
  isolation: isolate;
  padding: clamp(56px, 9vw, 104px) 0;
}

.page-about .tl-bg {
  position: absolute;
  inset: 0;
  z-index: -1;
  overflow: hidden;
}

.page-about .tl-bg img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.26;
}

.page-about .tl-bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    180deg,
    var(--ink-900) 0%,
    rgba(7, 26, 47, 0.7) 42%,
    var(--ink-900) 100%
  );
}

.page-about .tl-stages {
  display: grid;
  gap: clamp(44px, 7vw, 88px);
}

.page-about .tl-stage {
  display: grid;
  grid-template-columns: var(--rail-w) minmax(0, 1fr);
  gap: 0 18px;
  scroll-margin-top: calc(var(--header-space) + 24px);
}

@media (min-width: 960px) {
  .page-about .tl-stage {
    grid-template-columns: var(--rail-w) minmax(0, 1fr) minmax(0, 268px);
    gap: 0 38px;
    min-height: 50vh;
    align-content: center;
  }
}

.page-about .tl-rail {
  position: relative;
  display: flex;
  justify-content: center;
}

.page-about .tl-rail::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: -18px;
  left: 50%;
  width: 1px;
  background: var(--line-400);
  transform: translateX(-50%);
}

.page-about .tl-tick {
  position: relative;
  display: block;
  width: 26px;
  height: 3px;
  margin-top: 8px;
  background: var(--gold-400);
  transition: width 0.18s var(--ease), background 0.18s var(--ease);
}

.page-about .tl-tick::after {
  content: "";
  position: absolute;
  top: -3px;
  left: 50%;
  width: 9px;
  height: 9px;
  background: var(--gold-400);
  transform: translateX(-50%) rotate(45deg);
  transition: background 0.18s var(--ease);
}

.page-about .tl-tick:hover,
.page-about .tl-tick:focus-visible {
  width: 40px;
  background: var(--vermilion-500);
}

.page-about .tl-tick:hover::after,
.page-about .tl-tick:focus-visible::after {
  background: var(--vermilion-500);
}

.page-about .tl-num {
  margin: 0;
  font-family: var(--mono);
  font-size: clamp(40px, 8vw, 72px);
  font-weight: 500;
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--gold-400);
}

.page-about .tl-title {
  margin: 0.5em 0 0;
  font-size: var(--f-lg);
  line-height: 1.25;
  letter-spacing: -0.01em;
}

.page-about .tl-ver {
  margin: 8px 0 0;
  font-family: var(--serif);
  font-weight: 500;
  font-size: var(--f-sm);
  letter-spacing: 0.02em;
  color: var(--vermilion-500);
}

.page-about .tl-text {
  margin: 18px 0 0;
  max-width: 60ch;
  font-size: var(--f-sm);
  line-height: 1.8;
  color: var(--text-muted);
}

.page-about .tl-points {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 11px;
  max-width: 62ch;
}

.page-about .tl-points li {
  position: relative;
  padding-left: 24px;
  font-size: var(--f-sm);
  line-height: 1.72;
  color: var(--text-primary);
}

.page-about .tl-points li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 13px;
  height: 1px;
  background: var(--gold-600);
}

.page-about .tl-aside {
  grid-column: 2;
  margin-top: 28px;
  padding-left: 16px;
  border-left: 1px solid var(--line-400);
}

@media (min-width: 960px) {
  .page-about .tl-aside {
    grid-column: 3;
    margin-top: 4px;
    padding-left: 22px;
  }
}

.page-about .tl-aside-key {
  margin: 0;
  font-family: var(--mono);
  font-size: var(--f-2xs);
  letter-spacing: 0.14em;
  color: var(--text-muted);
}

.page-about .tl-aside-val {
  margin: 8px 0 0;
  font-size: var(--f-xs);
  line-height: 1.75;
  color: var(--gold-400);
}

/* ---------- 检索路径 ---------- */

.page-about .about-retrieval {
  padding: clamp(56px, 9vw, 100px) 0;
  background: var(--ink-800);
  border-top: 1px solid var(--line-400);
  border-bottom: 1px solid var(--line-400);
}

.page-about .retrieval-figure {
  margin: 0 0 clamp(28px, 4vw, 44px);
}

.page-about .retrieval-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line-400);
  filter: saturate(0.72) contrast(1.05);
}

@media (min-width: 900px) {
  .page-about .retrieval-figure {
    width: 66%;
  }
}

.page-about .retrieval-figure figcaption {
  margin-top: 12px;
  font-family: var(--mono);
  font-size: var(--f-2xs);
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.page-about .retrieval-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: about-step;
}

.page-about .retrieval-steps li {
  counter-increment: about-step;
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 0 16px;
  padding: 18px 0;
  border-top: 1px solid var(--line-400);
}

.page-about .retrieval-steps li:last-child {
  border-bottom: 1px solid var(--line-400);
}

.page-about .retrieval-steps li::before {
  content: counter(about-step, decimal-leading-zero);
  font-family: var(--mono);
  font-size: var(--f-sm);
  font-weight: 500;
  line-height: 1.7;
  color: var(--gold-400);
}

.page-about .retrieval-steps li > span {
  display: block;
  max-width: 68ch;
  font-size: var(--f-sm);
  line-height: 1.78;
  color: var(--text-primary);
}

/* ---------- 编目机制 ---------- */

.page-about .about-cataloging {
  padding: clamp(56px, 9vw, 100px) 0;
}

.page-about .cat-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 5vw, 56px);
}

@media (min-width: 900px) {
  .page-about .cat-grid {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr);
    align-items: start;
  }
}

.page-about .cat-lead {
  margin: 0;
  max-width: 62ch;
  font-size: var(--f-sm);
  line-height: 1.85;
  color: var(--text-muted);
}

.page-about .cat-rules {
  margin: 26px 0 0;
  display: grid;
  gap: 0;
}

.page-about .cat-rules > div {
  display: grid;
  gap: 7px;
  padding: 16px 0;
  border-top: 1px solid var(--line-400);
}

.page-about .cat-rules > div:last-child {
  border-bottom: 1px solid var(--line-400);
}

@media (min-width: 720px) {
  .page-about .cat-rules > div {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 0 22px;
    align-items: baseline;
  }
}

.page-about .cat-rules dt {
  font-family: var(--mono);
  font-size: var(--f-2xs);
  letter-spacing: 0.14em;
  color: var(--vermilion-500);
}

.page-about .cat-rules dd {
  margin: 0;
  max-width: 56ch;
  font-size: var(--f-sm);
  line-height: 1.78;
  color: var(--text-primary);
}

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

.page-about .cat-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line-400);
  filter: saturate(0.85);
  clip-path: polygon(
    0 0,
    calc(100% - var(--about-cut)) 0,
    100% var(--about-cut),
    100% 100%,
    0 100%
  );
}

.page-about .cat-figure figcaption {
  margin-top: 12px;
  font-size: var(--f-xs);
  line-height: 1.7;
  color: var(--text-muted);
}

/* ---------- 对照表 ---------- */

.page-about .about-mapping {
  padding: clamp(56px, 9vw, 100px) 0;
  background: var(--ink-800);
  border-top: 1px solid var(--line-400);
  border-bottom: 1px solid var(--line-400);
}

.page-about .map-wrap {
  border: 1px solid var(--line-400);
  background: var(--ink-900);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .map-table {
  width: 100%;
  min-width: 680px;
  border-collapse: collapse;
  font-size: var(--f-xs);
}

.page-about .map-table th {
  padding: 15px 18px;
  text-align: left;
  white-space: nowrap;
  font-family: var(--mono);
  font-weight: 500;
  font-size: var(--f-2xs);
  letter-spacing: 0.14em;
  color: var(--gold-400);
  border-bottom: 1px solid var(--line-400);
  background: var(--ink-950);
}

.page-about .map-table td {
  position: relative;
  padding: 17px 18px;
  vertical-align: top;
  line-height: 1.7;
  color: var(--text-muted);
  border-bottom: 1px solid rgba(36, 64, 95, 0.62);
}

.page-about .map-table tbody tr:last-child td {
  border-bottom: 0;
}

.page-about .map-table td:first-child {
  color: var(--text-primary);
}

.page-about .map-table td:nth-child(2) {
  color: var(--gold-400);
}

.page-about .map-table td:not(:last-child)::after {
  content: "";
  position: absolute;
  right: 0;
  top: 14%;
  bottom: 14%;
  width: 1px;
  background: linear-gradient(180deg, transparent, var(--slate-600), transparent);
  transform: rotate(var(--skew));
}

.page-about .map-table tbody tr {
  transition: background 0.18s var(--ease);
}

.page-about .map-table tbody tr:hover {
  background: rgba(255, 106, 43, 0.07);
}

.page-about .map-table tbody tr:hover td:first-child {
  box-shadow: inset 3px 0 0 var(--vermilion-500);
}

/* ---------- 维护团队 ---------- */

.page-about .about-team {
  padding: clamp(56px, 9vw, 100px) 0;
}

.page-about .team-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

@media (min-width: 900px) {
  .page-about .team-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 16px;
  }
}

.page-about .team-cell {
  padding: 18px;
  background: var(--ink-800);
  border: 1px solid var(--line-400);
}

.page-about .team-cell .n {
  margin: 0;
  font-family: var(--mono);
  font-size: var(--f-xl);
  font-weight: 500;
  line-height: 1.1;
  color: var(--gold-400);
}

.page-about .team-cell .k {
  margin: 8px 0 0;
  font-size: var(--f-xs);
  line-height: 1.6;
  letter-spacing: 0.04em;
  color: var(--text-muted);
}

.page-about .team-text {
  margin: 26px 0 0;
  max-width: 64ch;
  font-size: var(--f-sm);
  line-height: 1.82;
  color: var(--text-muted);
}

.page-about .team-cycles {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .team-cycles li {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 12px;
  padding: 13px 0;
  border-top: 1px solid var(--line-400);
  font-size: var(--f-sm);
  line-height: 1.7;
  color: var(--text-primary);
}

.page-about .team-cycles li:last-child {
  border-bottom: 1px solid var(--line-400);
}

.page-about .team-cycles .mono {
  flex: 0 0 auto;
  min-width: 96px;
  font-family: var(--mono);
  font-size: var(--f-2xs);
  letter-spacing: 0.12em;
  color: var(--vermilion-500);
}

/* ---------- 收尾 ---------- */

.page-about .about-tail {
  padding: clamp(36px, 6vw, 64px) 0 clamp(56px, 9vw, 96px);
}

.page-about .tail-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px 20px;
  padding: 16px 0;
  border-top: 2px solid var(--vermilion-500);
  border-bottom: 1px solid var(--line-400);
}

.page-about .tail-key {
  margin: 0;
  font-family: var(--mono);
  font-size: var(--f-2xs);
  letter-spacing: 0.16em;
  color: var(--text-muted);
}

.page-about .tail-val {
  margin: 0;
  font-family: var(--mono);
  font-size: var(--f-sm);
  font-weight: 500;
  color: var(--gold-400);
}

.page-about .tail-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 26px;
}

.page-about .tail-links a {
  display: inline-flex;
  align-items: center;
  padding: 10px 18px;
  font-size: var(--f-xs);
  letter-spacing: 0.04em;
  text-decoration: none;
  color: var(--text-primary);
  background: var(--ink-800);
  border: 1px solid var(--line-400);
  clip-path: polygon(0 0, calc(100% - 10px) 0, 100% 10px, 100% 100%, 0 100%);
  transition: border-color 0.18s var(--ease), color 0.18s var(--ease), background 0.18s var(--ease);
}

.page-about .tail-links a:hover,
.page-about .tail-links a:focus-visible {
  border-color: var(--vermilion-500);
  background: rgba(255, 106, 43, 0.1);
  color: var(--vermilion-500);
}

/* ---------- 动效降级 ---------- */

@media (prefers-reduced-motion: reduce) {
  .page-about [data-reveal] {
    transform: none;
    transition: opacity 0.2s linear;
  }

  .page-about .tl-tick,
  .page-about .tl-tick::after,
  .page-about .hero-side-link,
  .page-about .tail-links a,
  .page-about .map-table tbody tr {
    transition: none;
  }
}