.page-about {
  --ab-rule: 1px solid var(--line);
  --ab-gap: clamp(24px, 4vw, 48px);
}

.page-about img {
  max-width: 100%;
  height: auto;
}

.page-about h1,
.page-about h2,
.page-about h3 {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about h1 {
  font-size: clamp(30px, 6.2vw, 52px);
  line-height: 1.15;
  margin: 0 0 16px;
}

.page-about h2 {
  font-size: clamp(23px, 3.6vw, 34px);
  line-height: 1.26;
  margin: 0 0 12px;
}

.page-about h3 {
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.42;
  margin: 0 0 8px;
}

.page-about p {
  margin: 0 0 15px;
}

.page-about .tb-crumb {
  padding-top: clamp(16px, 2.4vw, 26px);
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  padding: clamp(20px, 3.4vw, 34px) 0 clamp(32px, 5vw, 68px);
}

.page-about .ab-hero__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 4vw, 44px);
  padding-top: clamp(18px, 3vw, 30px);
  border-top: 2px solid var(--indigo);
}

.page-about .ab-hero__lede {
  font-size: clamp(16px, 1.9vw, 18px);
  line-height: 1.85;
  color: var(--ink-soft);
  max-width: 62ch;
}

.page-about .ab-hero__sub {
  font-size: 15px;
  line-height: 1.8;
  color: var(--muted);
  padding-left: 14px;
  border-left: 2px solid var(--teal);
  max-width: 56ch;
}

.page-about .ab-hero__acts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 22px;
}

.page-about .ab-hero__panel {
  background: var(--indigo-deep);
  padding: clamp(18px, 3vw, 28px);
  display: grid;
  gap: 16px;
  align-content: start;
}

.page-about .ab-hero__svg {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .ab-hero__cap {
  margin: 0;
  font-size: 13px;
  line-height: 1.75;
  letter-spacing: 0.02em;
  color: rgba(247, 247, 244, 0.72);
}

/* ---------- 侧轨 + 正文 ---------- */
.page-about .ab-shell {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--ab-gap);
  padding-bottom: clamp(40px, 6vw, 84px);
}

.page-about .ab-rail {
  border-top: 2px solid var(--ink);
  padding-top: 14px;
}

.page-about .ab-rail__title {
  margin: 0 0 10px;
  font-family: var(--font-ui);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

.page-about .ab-rail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0 14px;
}

.page-about .ab-rail__item {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 9px 0;
  border-bottom: 1px solid var(--line);
  font-family: var(--font-ui);
  font-size: 14px;
  color: var(--muted);
}

.page-about .ab-rail__n {
  font-variant-numeric: tabular-nums;
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--line);
}

.page-about .ab-rail__item.is-current {
  color: var(--indigo);
  font-weight: 600;
}

.page-about .ab-rail__item.is-current .ab-rail__n {
  color: var(--amber);
}

.page-about .ab-rail__note {
  margin: 16px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 章节 ---------- */
.page-about .ab-sec {
  padding: clamp(32px, 5vw, 62px) 0;
  border-top: 1px solid var(--line);
}

.page-about .ab-body > .ab-sec:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .ab-sec__lede {
  font-size: 16px;
  line-height: 1.85;
  color: var(--ink-soft);
  max-width: 64ch;
}

.page-about .ab-note {
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
  padding-left: 16px;
  border-left: 2px solid var(--teal-mist);
  max-width: 66ch;
}

/* ---------- 图片 ---------- */
.page-about .ab-figure {
  margin: 24px 0 4px;
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  background: var(--indigo-soft);
  border: 1px solid var(--line);
}

.page-about .ab-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.7;
  letter-spacing: 0.02em;
  color: var(--muted);
}

.page-about .ab-figure--narrow {
  max-width: 620px;
}

.page-about .ab-figure--square {
  max-width: 100%;
  margin-top: 18px;
}

/* ---------- 时间线 ---------- */
.page-about .ab-tl {
  list-style: none;
  margin: 28px 0 0;
  padding: 0 0 0 22px;
  border-left: 1px solid var(--line);
}

.page-about .ab-tl__item {
  position: relative;
  padding: 0 0 26px 6px;
}

.page-about .ab-tl__item:last-child {
  padding-bottom: 0;
}

.page-about .ab-tl__item::before {
  content: "";
  position: absolute;
  left: -27px;
  top: 6px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--paper);
  border: 1px solid var(--line);
  transition: background var(--t-fast), border-color var(--t-fast);
}

.page-about .ab-tl__item:hover::before,
.page-about .ab-tl__item:focus-within::before {
  background: var(--amber-glow);
  border-color: var(--amber);
}

.page-about .ab-tl__item--now::before {
  background: var(--indigo);
  border-color: var(--indigo);
}

.page-about .ab-tl__year {
  display: inline-block;
  font-family: var(--font-ui);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: 5px;
  font-variant-numeric: tabular-nums;
}

.page-about .ab-tl__body h3 {
  transition: color var(--t-fast);
}

.page-about .ab-tl__item:hover .ab-tl__body h3 {
  color: var(--indigo);
}

.page-about .ab-tl__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
}

/* ---------- 主栏 + 旁注 ---------- */
.page-about .ab-split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
  margin-top: 20px;
}

.page-about .ab-split__main p {
  font-size: 16px;
  line-height: 1.9;
  color: var(--ink-soft);
}

.page-about .ab-aside {
  background: var(--indigo-soft);
  border-left: 3px solid var(--indigo);
  padding: 20px 18px;
}

.page-about .ab-aside__k {
  margin: 0 0 12px;
  font-family: var(--font-ui);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--indigo);
}

.page-about .ab-aside__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 11px;
}

.page-about .ab-aside__list li {
  position: relative;
  padding-left: 16px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--ink-soft);
}

.page-about .ab-aside__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: 6px;
  height: 6px;
  background: var(--teal);
}

.page-about .ab-stat {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 9px 0;
  border-bottom: 1px solid rgba(35, 44, 107, 0.16);
}

.page-about .ab-stat:last-child {
  border-bottom: 0;
}

.page-about .ab-stat__n {
  font-family: var(--font-ui);
  font-variant-numeric: tabular-nums;
  font-size: 26px;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--indigo);
  line-height: 1.1;
}

.page-about .ab-stat__k {
  font-family: var(--font-ui);
  font-size: 14px;
  color: var(--ink-soft);
}

/* ---------- 标签阵列 ---------- */
.page-about .ab-rings {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.page-about .ab-ring {
  border: 1px solid var(--line);
  background: var(--white);
  padding: 16px 14px 18px;
  transition: border-color var(--t-fast), background var(--t-fast);
}

.page-about .ab-ring:hover,
.page-about .ab-ring:focus-within {
  border-color: var(--indigo);
  background: var(--indigo-soft);
}

.page-about .ab-ring__n {
  display: block;
  font-family: var(--font-ui);
  font-variant-numeric: tabular-nums;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--muted);
  margin-bottom: 10px;
}

.page-about .ab-ring h3 {
  margin: 0;
  font-family: var(--font-ui);
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1.4;
}

/* ---------- 三道关 ---------- */
.page-about .ab-check {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .ab-check__d {
  border: 1px solid var(--line);
  background: var(--white);
  transition: border-color var(--t-fast);
}

.page-about .ab-check__d:hover {
  border-color: var(--indigo);
}

.page-about .ab-check__d summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 15px 18px;
  font-family: var(--font-ui);
  font-size: 16px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--ink);
}

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

.page-about .ab-check__d summary::after {
  content: "+";
  margin-left: auto;
  font-weight: 600;
  color: var(--amber);
  transition: color var(--t-fast);
}

.page-about .ab-check__d[open] summary::after {
  content: "–";
}

.page-about .ab-check__n {
  font-family: var(--font-ui);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--teal);
}

.page-about .ab-check__d p {
  margin: 0;
  padding: 0 18px 18px 44px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
}

/* ---------- 收尾 ---------- */
.page-about .ab-cta {
  margin-top: 24px;
  background: var(--indigo-deep);
  padding: clamp(22px, 3.4vw, 34px);
  display: grid;
  gap: 18px;
  align-items: center;
}

.page-about .ab-cta p {
  margin: 0;
  font-size: 16px;
  line-height: 1.85;
  color: rgba(247, 247, 244, 0.86);
}

.page-about .ab-more {
  margin-top: 20px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
}

.page-about .ab-body a {
  color: var(--indigo);
  text-decoration: none;
  border-bottom: 1px solid var(--teal);
  transition: color var(--t-fast), border-color var(--t-fast);
}

.page-about .ab-body a:hover,
.page-about .ab-body a:focus-visible {
  color: var(--amber);
  border-color: var(--amber);
}

.page-about .tb-btn {
  border-bottom: 0;
}

/* ---------- 断点 ---------- */
@media (min-width: 720px) {
  .page-about .ab-rings {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .ab-cta {
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 28px;
  }

  .page-about .ab-figure--square {
    max-width: 420px;
  }
}

@media (min-width: 900px) {
  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.28fr) minmax(0, 0.82fr);
    align-items: start;
  }

  .page-about .ab-split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: clamp(24px, 3.4vw, 44px);
    align-items: start;
  }

  .page-about .ab-aside {
    margin-top: -22px;
  }

  .page-about .ab-aside--stats {
    margin-top: 6px;
  }

  .page-about .ab-split--flip .ab-split__main {
    order: 1;
  }

  .page-about .ab-figure--square {
    margin-top: 0;
  }
}

@media (min-width: 1040px) {
  .page-about .ab-shell {
    grid-template-columns: minmax(0, 3.4fr) minmax(0, 8.6fr);
  }

  .page-about .ab-rail {
    position: sticky;
    top: calc(var(--header-h) + 22px);
    align-self: start;
  }

  .page-about .ab-rail__list {
    display: grid;
    gap: 0;
  }

  .page-about .ab-rail__item {
    gap: 10px;
  }
}
<<<END>>>