.page-about {
  --ab-line: rgba(74, 88, 114, 0.42);
  --ab-soft: rgba(34, 231, 200, 0.14);
}

.page-about section[id] {
  scroll-margin-top: 104px;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(28px, 5vw, 54px);
  padding: clamp(22px, 4vw, 40px) 0 clamp(36px, 7vw, 84px);
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-hero-nav {
  align-self: start;
}

.page-about .ab-index {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
}

.page-about .ab-index a {
  display: grid;
  grid-template-columns: 26px 1fr;
  gap: 8px;
  padding: 7px 0;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.5;
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur), border-color var(--dur);
}

.page-about .ab-index a span {
  color: var(--rule);
}

.page-about .ab-index a:hover,
.page-about .ab-index a:focus-visible {
  color: var(--text);
  border-bottom-color: var(--cyan);
}

.page-about .ab-index a:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.page-about .ab-h1 {
  margin: 14px 0 0;
  font-size: clamp(30px, 5.4vw, 54px);
  font-weight: 800;
  line-height: 1.12;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .ab-hero-body .lede {
  margin: 20px 0 0;
  max-width: 62ch;
}

.page-about .ab-facts {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(20px, 4vw, 48px);
  margin: 32px 0 0;
  padding-top: 22px;
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-facts .metric {
  display: block;
}

.page-about .ab-facts .metric-value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.2vw, 36px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--cyan);
}

.page-about .ab-facts .metric-label {
  display: block;
  margin-top: 9px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.page-about .ab-hero-media {
  margin: clamp(28px, 5vw, 48px) 0 0;
}

/* ---------- 章节骨架 ---------- */
.page-about .ab-chapter {
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-chapter-aside {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding-bottom: 14px;
}

.page-about .ab-num {
  font-family: var(--font-mono);
  font-size: clamp(26px, 4vw, 42px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--cyan);
}

.page-about .ab-chapter-body h2 {
  margin: 0 0 18px;
  font-size: clamp(22px, 3vw, 32px);
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .ab-chapter-body h3 {
  margin: 0;
  font-size: 17px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--text);
}

.page-about .ab-chapter-body .prose p {
  margin: 0 0 18px;
}

/* ---------- 01 原则 ---------- */
.page-about .ab-principles {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
  counter-reset: ab-principle;
}

.page-about .ab-principle {
  display: grid;
  gap: 10px;
  align-content: start;
  padding: 20px 20px 22px;
}

.page-about .ab-principle-num {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--cyan);
}

.page-about .ab-principle p {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--muted);
}

/* ---------- 02 来源 ---------- */
.page-about .ab-sources {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .ab-sources > li {
  padding: 20px 0 22px;
  border-top: 1px solid var(--ab-line);
  display: grid;
  gap: 8px;
  align-content: start;
}

.page-about .ab-src-tag {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--yellow);
}

.page-about .ab-sources p {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--muted);
}

.page-about .ab-check {
  display: grid;
  gap: clamp(22px, 4vw, 36px);
  margin: 34px 0 0;
  padding-top: 26px;
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-check-body h3 {
  margin-bottom: 12px;
}

.page-about .ab-check-body p {
  margin: 0 0 20px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .ab-flow {
  display: block;
  width: 100%;
  max-width: 460px;
  height: auto;
}

.page-about .ab-flow-path {
  stroke: var(--rule);
  transition: stroke var(--dur), stroke-width var(--dur);
}

.page-about .ab-flow-path:hover {
  stroke: var(--cyan);
  stroke-width: 2.6;
}

.page-about .ab-flow-path--out {
  stroke-dasharray: 6 5;
}

.page-about .ab-check-media {
  margin: 0;
}

/* ---------- 03 编辑室 ---------- */
.page-about .ab-desk {
  display: grid;
  gap: clamp(26px, 4vw, 44px);
  margin: 30px 0 0;
}

.page-about .ab-desk-title {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.12em;
  color: var(--muted);
  margin: 0 0 6px;
}

.page-about .ab-teams,
.page-about .ab-shifts {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .ab-team,
.page-about .ab-shift {
  padding: 16px 0;
  border-top: 1px solid var(--ab-line);
  display: grid;
  gap: 6px;
}

.page-about .ab-team-name {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--cyan);
}

.page-about .ab-team p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .ab-shift-key {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--text);
}

.page-about .ab-shift-val {
  font-size: 14px;
  line-height: 1.75;
  color: var(--muted);
}

/* ---------- 04 时间轴 ---------- */
.page-about .ab-timeline-shell {
  position: relative;
  margin: 30px 0 0;
  overflow: hidden;
  border-radius: var(--radius-lg);
}

.page-about .ab-timeline-media {
  position: absolute;
  inset: 0;
  margin: 0;
  opacity: 0.14;
  pointer-events: none;
}

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

.page-about .ab-timeline-content {
  position: relative;
  padding: 24px 0 8px;
}

.page-about .ab-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
}

.page-about .ab-tl-item {
  flex: 0 0 168px;
  scroll-snap-align: start;
}

.page-about .ab-tl-node {
  position: relative;
  display: grid;
  gap: 7px;
  width: 100%;
  padding: 18px 14px 16px 0;
  background: none;
  border: 0;
  border-top: 1px solid var(--ab-line);
  text-align: left;
  cursor: pointer;
  color: var(--muted);
  transition: color var(--dur);
}

.page-about .ab-tl-node::before {
  content: "";
  position: absolute;
  top: -4px;
  left: 0;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--rule);
  transition: background var(--dur), box-shadow var(--dur);
}

.page-about .ab-tl-node:hover::before,
.page-about .ab-tl-node:focus-visible::before {
  background: var(--cyan);
  box-shadow: 0 0 0 4px var(--ab-soft);
}

.page-about .ab-tl-node:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.page-about .ab-tl-node[aria-expanded="true"]::before {
  background: var(--cyan);
}

.page-about .ab-tl-year {
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--text);
}

.page-about .ab-tl-node[aria-expanded="true"] .ab-tl-year {
  color: var(--cyan);
}

.page-about .ab-tl-name {
  font-size: 12px;
  line-height: 1.5;
  color: var(--muted);
}

.page-about .ab-tl-panel {
  margin-top: 20px;
  padding: 18px 20px;
  background: var(--panel);
  border-left: 2px solid var(--cyan);
  border-radius: var(--radius);
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .ab-tl-panel[hidden] {
  display: none;
}

/* ---------- 05 边界 ---------- */
.page-about .ab-boundaries {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-boundary {
  display: grid;
  gap: 10px;
  align-content: start;
  padding: 20px 20px 22px;
  border-left: 2px solid rgba(255, 77, 46, 0.6);
}

.page-about .ab-bd-mark {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--orange);
}

.page-about .ab-boundary p {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--muted);
}

.page-about .ab-boundary-note {
  margin: 24px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
}

/* ---------- 06 备案 ---------- */
.page-about .ab-registry {
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .ab-registry-row {
  display: grid;
  gap: 6px;
  padding: 15px 0;
  border-top: 1px solid var(--ab-line);
}

.page-about .ab-registry-row dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.page-about .ab-registry-row dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 14px;
  line-height: 1.6;
  color: var(--text);
  word-break: break-word;
}

.page-about .ab-registry-note {
  margin: 26px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .ab-registry-note a,
.page-about .ab-boundary-note a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(34, 231, 200, 0.4);
  transition: border-color var(--dur);
}

.page-about .ab-registry-note a:hover,
.page-about .ab-registry-note a:focus-visible,
.page-about .ab-boundary-note a:hover,
.page-about .ab-boundary-note a:focus-visible {
  border-bottom-color: var(--cyan);
}

.page-about .ab-registry-note a:focus-visible,
.page-about .ab-boundary-note a:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

/* ---------- 休息带 ---------- */
.page-about .ab-rest {
  padding-top: clamp(36px, 6vw, 72px);
  padding-bottom: clamp(36px, 6vw, 72px);
}

.page-about .ab-rest-line {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(12px, 1.6vw, 15px);
  letter-spacing: 0.14em;
  color: var(--rule);
  text-align: center;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .ab-sources {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: clamp(22px, 4vw, 48px);
  }
}

@media (min-width: 900px) {
  .page-about .ab-hero {
    grid-template-columns: minmax(150px, 196px) minmax(0, 1fr);
    gap: clamp(36px, 6vw, 76px);
  }

  .page-about .ab-hero-nav {
    position: sticky;
    top: 104px;
  }

  .page-about .ab-chapter-aside {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    padding-bottom: 0;
    padding-right: 26px;
    border-right: 1px solid var(--ab-line);
  }

  .page-about .ab-principles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .ab-check {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    align-items: start;
  }

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

  .page-about .ab-timeline-content {
    padding: 32px 0 12px;
  }

  .page-about .ab-tl-item {
    flex: 1 1 0;
    min-width: 140px;
  }

  .page-about .ab-timeline {
    overflow-x: visible;
  }

  .page-about .ab-registry-row {
    grid-template-columns: 120px minmax(0, 1fr);
    gap: 18px;
    align-items: baseline;
  }
}

@media (max-width: 899px) {
  .page-about .ab-chapter-aside {
    border-bottom: 1px solid var(--ab-line);
    margin-bottom: 22px;
  }
}

@media (max-width: 560px) {
  .page-about .ab-shift {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .page-about .ab-facts {
    gap: 20px 28px;
  }

  .page-about .ab-registry-row dd {
    font-size: 13px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-flow-path,
  .page-about .ab-tl-node,
  .page-about .ab-tl-node::before,
  .page-about .ab-index a {
    transition: none;
  }
}