.page-about {
  --ab-rail-w: 196px;
  --ab-col-gap: 44px;
  --ab-panel-shadow: var(--hb-shadow-soft);
}

.page-about .ab-crumb {
  padding-top: calc(var(--hb-header-h) + 18px);
  padding-bottom: 2px;
}

/* ---------- 首屏 ---------- */

.page-about .ab-hero {
  padding-bottom: 8px;
}

.page-about .ab-hero__inner {
  display: grid;
  gap: 16px;
  padding-top: 30px;
  padding-bottom: 30px;
}

.page-about .ab-hero__eyebrow {
  margin: 0;
}

.page-about .ab-hero__title {
  margin: 0;
  font-size: clamp(38px, 7.4vw, 88px);
  line-height: 1.02;
  letter-spacing: -0.03em;
  font-weight: 200;
  color: var(--hb-ink);
  max-width: 15ch;
}

.page-about .ab-hero__title strong {
  display: block;
  font-weight: 700;
  color: var(--hb-turf);
}

.page-about .ab-hero__lead {
  max-width: 62ch;
  margin: 2px 0 0;
  color: var(--hb-gray);
}

.page-about .ab-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 14px 0 0;
  padding: 0;
  background: var(--hb-rule);
  border-radius: var(--hb-radius-md);
  overflow: hidden;
}

.page-about .ab-facts__item {
  background: var(--hb-paper);
  padding: 16px 18px;
  display: grid;
  gap: 2px;
}

.page-about .ab-facts__num {
  font-size: clamp(24px, 3.4vw, 34px);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.05;
  color: var(--hb-turf-deep);
  font-variant-numeric: tabular-nums;
}

.page-about .ab-facts__label {
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--hb-gray);
}

.page-about .ab-hero__figure {
  padding-bottom: 8px;
}

.page-about .ab-hero__media {
  border-radius: var(--hb-radius-lg);
  overflow: hidden;
  box-shadow: 0 30px 60px -46px rgba(11, 15, 18, 0.6);
}

.page-about .ab-hero__media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

/* ---------- 主体网格 ---------- */

.page-about .ab-body {
  padding: 26px 0 8px;
}

.page-about .ab-body__grid {
  display: grid;
  gap: 18px;
}

/* 章节索引（移动端为横向胶囊条） */

.page-about .ab-rail {
  position: relative;
  display: flex;
  align-items: center;
  gap: 10px;
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 2px 10px;
  scrollbar-width: none;
}

.page-about .ab-rail::-webkit-scrollbar {
  display: none;
}

.page-about .ab-rail__label {
  display: none;
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--hb-gray);
}

.page-about .ab-rail__list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .ab-rail__link {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-height: 44px;
  padding: 0 15px;
  border-radius: 999px;
  border: 1px solid var(--hb-rule);
  background: var(--hb-paper);
  color: var(--hb-ink);
  text-decoration: none;
  white-space: nowrap;
  font-size: 14px;
  transition: background-color var(--hb-dur) var(--hb-ease),
    border-color var(--hb-dur) var(--hb-ease),
    transform var(--hb-dur) var(--hb-ease);
}

.page-about .ab-rail__link:hover,
.page-about .ab-rail__link:focus-visible {
  background: var(--hb-mint);
  border-color: var(--hb-turf-light);
  transform: translateY(-2px);
}

.page-about .ab-rail__num {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--hb-ember);
  font-variant-numeric: tabular-nums;
}

.page-about .ab-rail__track {
  display: none;
}

/* 章节画板 */

.page-about .ab-flow {
  display: grid;
}

.page-about .ab-chapter {
  position: relative;
  overflow: hidden;
  margin: 0 0 20px;
  padding: clamp(26px, 4.2vw, 46px) clamp(20px, 4vw, 42px);
  border-radius: var(--hb-radius-lg);
  box-shadow: var(--ab-panel-shadow);
  scroll-margin-top: calc(var(--hb-header-h) + 26px);
}

.page-about .ab-chapter__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 16px;
}

.page-about .ab-chapter__num {
  position: absolute;
  right: 10px;
  bottom: 2px;
  z-index: 0;
  font-size: clamp(96px, 17vw, 210px);
  font-weight: 700;
  line-height: 0.7;
  letter-spacing: -0.06em;
  opacity: 0.07;
  color: currentColor;
  pointer-events: none;
  user-select: none;
}

.page-about .ab-chapter__title {
  margin: 0;
  font-size: clamp(26px, 3.6vw, 44px);
  line-height: 1.14;
  letter-spacing: -0.02em;
  font-weight: 600;
}

.page-about .ab-chapter__lead {
  margin: 0;
  max-width: 56ch;
}

.page-about .ab-chapter__split {
  display: grid;
  gap: 22px;
}

.page-about .ab-chapter__text {
  max-width: 62ch;
}

.page-about .ab-chapter__figure {
  border-radius: var(--hb-radius-md);
  overflow: hidden;
}

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

.page-about .ab-chapter__note {
  margin: 0;
  font-size: 14px;
  color: var(--hb-gray);
}

.page-about .ab-chapter__note a {
  color: var(--hb-turf-light);
  text-underline-offset: 4px;
}

.page-about .ab-quote {
  margin: 4px 0 0;
}

/* 五条内容线 */

.page-about .ab-lines {
  display: grid;
  gap: 0;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: none;
}

.page-about .ab-lines__item {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 4px 14px;
  padding: 18px 0;
  border-top: 1px solid var(--hb-rule);
}

.page-about .ab-lines__item:last-child {
  border-bottom: 1px solid var(--hb-rule);
}

.page-about .ab-lines__idx {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--hb-turf-light);
  font-variant-numeric: tabular-nums;
  padding-top: 4px;
}

.page-about .ab-lines__main {
  display: grid;
  gap: 6px;
}

.page-about .ab-lines__title {
  margin: 0;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .ab-lines__text {
  margin: 0;
  max-width: 60ch;
  color: var(--hb-gray);
  line-height: 1.75;
}

.page-about .ab-lines__tag {
  grid-column: 2;
  justify-self: start;
  margin-top: 2px;
}

/* 版本时间线 */

.page-about .ab-timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 26px;
  list-style: none;
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: currentColor;
  opacity: 0.28;
}

.page-about .ab-timeline__item {
  position: relative;
  padding-bottom: 24px;
}

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

.page-about .ab-timeline__item::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 6px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--hb-ember);
  box-shadow: 0 0 0 4px rgba(255, 106, 19, 0.16);
}

.page-about .ab-timeline__year {
  display: block;
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.1;
  font-variant-numeric: tabular-nums;
}

.page-about .ab-timeline__body {
  margin-top: 4px;
  display: grid;
  gap: 4px;
}

.page-about .ab-timeline__title {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
}

.page-about .ab-timeline__body p {
  margin: 0;
  max-width: 52ch;
  font-size: 15px;
  line-height: 1.7;
  opacity: 0.86;
}

/* ---------- 收束 ---------- */

.page-about .ab-coda {
  margin-top: 26px;
  background:
    radial-gradient(120% 140% at 88% 0%, rgba(46, 138, 92, 0.5) 0%, rgba(14, 42, 31, 0) 62%),
    var(--hb-turf-deep);
  color: var(--hb-mint);
  border-radius: var(--hb-radius-lg) var(--hb-radius-lg) 0 0;
}

.page-about .ab-coda__inner {
  display: grid;
  gap: 14px;
  padding-top: 52px;
  padding-bottom: 56px;
}

.page-about .ab-coda__title {
  margin: 0;
  font-size: clamp(28px, 4.4vw, 52px);
  line-height: 1.08;
  letter-spacing: -0.025em;
  font-weight: 300;
  color: #fff;
  max-width: 20ch;
}

.page-about .ab-coda__text {
  margin: 0;
  max-width: 58ch;
  line-height: 1.75;
  color: var(--hb-mint);
  opacity: 0.9;
}

.page-about .ab-coda__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 8px;
}

.page-about .ab-coda__actions .hb-btn {
  min-height: 44px;
}

/* ---------- 平板及以上 ---------- */

@media (min-width: 700px) {
  .page-about .ab-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .ab-hero__inner {
    padding-top: 44px;
    padding-bottom: 34px;
  }

  .page-about .ab-chapter__split {
    grid-template-columns: minmax(0, 1fr) minmax(0, 320px);
    align-items: start;
  }

  .page-about .ab-chapter__split--rev {
    grid-template-columns: minmax(0, 320px) minmax(0, 1fr);
  }

  .page-about .ab-chapter__split--rev .ab-chapter__figure {
    order: 2;
  }

  .page-about .ab-chapter__split--rev .ab-timeline {
    order: 1;
  }

  .page-about .ab-lines__item {
    grid-template-columns: 44px minmax(0, 1fr) auto;
    align-items: start;
    gap: 4px 18px;
  }

  .page-about .ab-lines__tag {
    grid-column: 3;
    grid-row: 1;
    justify-self: end;
    margin-top: 4px;
  }
}

/* ---------- 桌面：左侧纵向索引 ---------- */

@media (min-width: 980px) {
  .page-about .ab-body {
    padding-top: 34px;
  }

  .page-about .ab-body__grid {
    grid-template-columns: var(--ab-rail-w) minmax(0, 1fr);
    gap: var(--ab-col-gap);
    align-items: start;
  }

  .page-about .ab-rail {
    position: sticky;
    top: calc(var(--hb-header-h) + 28px);
    display: block;
    overflow: visible;
    padding: 0 0 0 20px;
    border-left: 1px solid var(--hb-rule);
  }

  .page-about .ab-rail__label {
    display: block;
    margin-bottom: 12px;
  }

  .page-about .ab-rail__list {
    display: grid;
    gap: 2px;
  }

  .page-about .ab-rail__link {
    min-height: 40px;
    padding: 0 12px 0 0;
    border: 0;
    border-radius: var(--hb-radius-nub);
    background: transparent;
    font-size: 15px;
  }

  .page-about .ab-rail__link:hover,
  .page-about .ab-rail__link:focus-visible {
    background: transparent;
    color: var(--hb-turf);
    transform: translateX(4px);
  }

  .page-about .ab-rail__track {
    display: block;
    position: absolute;
    left: -1px;
    top: 0;
    width: 2px;
    height: 100%;
    border-radius: 2px;
    background: linear-gradient(180deg, var(--hb-ember), var(--hb-turf-light));
    transform-origin: top center;
    transform: scaleY(0.04);
  }

  @supports (animation-timeline: scroll()) {
    .page-about .ab-rail__track {
      transform: scaleY(0);
      animation: ab-rail-progress 1s linear both;
      animation-timeline: scroll(root block);
    }
  }

  .page-about .ab-chapter {
    margin-bottom: 24px;
  }

  .page-about .ab-chapter:nth-child(odd) {
    margin-right: 22px;
  }

  .page-about .ab-chapter:nth-child(even) {
    margin-left: 22px;
  }

  .page-about .ab-chapter + .ab-chapter {
    margin-top: -6px;
  }
}

@keyframes ab-rail-progress {
  from {
    transform: scaleY(0);
  }
  to {
    transform: scaleY(1);
  }
}

/* ---------- 引文与卡片交互 ---------- */

.page-about .ab-quote {
  transition: transform var(--hb-dur) var(--hb-ease),
    box-shadow var(--hb-dur) var(--hb-ease);
}

.page-about .ab-quote:hover {
  transform: translateY(-3px);
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-rail__link,
  .page-about .ab-quote {
    transition: none;
  }

  .page-about .ab-rail__link:hover,
  .page-about .ab-rail__link:focus-visible,
  .page-about .ab-quote:hover {
    transform: none;
  }

  .page-about .ab-rail__track {
    animation: none;
    transform: scaleY(0.04);
  }
}
<<<END>>>