.page-about {
  --ab-rail-w: 92px;
  --ab-pad-y: clamp(38px, 5.5vw, 72px);
  --ab-shadow: 0 2px 12px rgba(0, 0, 0, .3);
  background-color: var(--ink);
  color: var(--paper);
  font-family: var(--font-body);
  overflow-x: clip;
}

/* ---------- 面包屑条 ---------- */
.page-about .ab-crumbbar {
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
  background: rgba(16, 50, 58, .5);
  font-size: 14px;
}

.page-about .ab-crumbbar a {
  color: var(--blue);
  text-decoration: none;
}

.page-about .ab-crumbbar a:hover,
.page-about .ab-crumbbar a:focus-visible {
  text-decoration: underline;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  border-bottom: 1px solid var(--line);
  background-color: var(--ink);
  background-image:
    repeating-linear-gradient(90deg, rgba(241, 246, 243, .04) 0 1px, transparent 1px 44px),
    radial-gradient(130% 100% at 8% -10%, rgba(12, 58, 43, .92), transparent 62%),
    radial-gradient(90% 80% at 100% 0%, rgba(110, 27, 38, .32), transparent 58%);
}

.page-about .ab-hero__inner {
  display: grid;
  gap: 30px;
  padding: clamp(36px, 6vw, 72px) 0 clamp(30px, 5vw, 60px);
}

.page-about .ab-kicker {
  margin: 0 0 14px;
  font-size: 12px;
  letter-spacing: .14em;
  font-weight: 700;
  color: var(--yellow);
}

.page-about .ab-hero__lede h1 {
  margin: 0 0 18px;
  font-family: var(--font-display);
  font-size: clamp(32px, 6.2vw, 68px);
  line-height: 1.06;
  font-weight: 900;
  letter-spacing: -.02em;
}

.page-about .ab-hero__text {
  margin: 0 0 24px;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--moss);
}

.page-about .ab-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .ab-board {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  padding: 14px;
  border: 1px solid var(--line);
  background: linear-gradient(150deg, rgba(16, 50, 58, .78), rgba(6, 17, 12, .35));
  box-shadow: var(--ab-shadow);
}

.page-about .ab-board__cell {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 14px 12px;
  border: 1px solid var(--line);
  background: rgba(6, 17, 12, .45);
}

.page-about .ab-board__num {
  font-size: clamp(24px, 3.2vw, 38px);
  letter-spacing: -.03em;
}

.page-about .ab-board__num em {
  font-size: 13px;
  font-style: normal;
  letter-spacing: .1em;
  margin-left: 4px;
}

.page-about .ab-board__label {
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--moss);
}

/* ---------- 外壳：轨道 + 长卷 ---------- */
.page-about .ab-shell {
  display: grid;
}

.page-about .ab-flow {
  min-width: 0;
}

/* ---------- 左侧章节轨道 ---------- */
.page-about .ab-rail {
  border-bottom: 1px solid var(--line);
  background: rgba(16, 50, 58, .45);
}

.page-about .ab-rail__list {
  display: flex;
  gap: 4px;
  margin: 0;
  padding: 10px 12px;
  list-style: none;
  overflow-x: auto;
}

.page-about .ab-rail__node {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-left: 2px solid transparent;
  color: var(--moss);
  font-size: 13px;
  text-decoration: none;
  white-space: nowrap;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .ab-rail__num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--moss-dim);
  transition: color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .ab-rail__node:hover,
.page-about .ab-rail__node:focus-visible {
  color: var(--yellow);
  border-left-color: var(--yellow);
  background: rgba(242, 195, 27, .07);
}

.page-about .ab-rail__node:hover .ab-rail__num,
.page-about .ab-rail__node:focus-visible .ab-rail__num {
  color: var(--yellow);
  transform: scale(1.18);
}

/* ---------- 章节 ---------- */
.page-about .ab-section {
  position: relative;
  padding: var(--ab-pad-y) clamp(18px, 4vw, 56px);
  border-bottom: 1px solid var(--line);
  scroll-margin-top: calc(var(--topbar-h) + 20px);
}

.page-about .ab-section::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 4px;
  background: var(--pitch);
}

.page-about .ab-section:nth-child(even)::before {
  background: var(--wine);
}

.page-about .ab-section:target {
  background: linear-gradient(90deg, rgba(242, 195, 27, .06), transparent 42%);
}

.page-about .ab-section:target::before {
  background: var(--yellow);
}

.page-about .ab-section__head {
  display: grid;
  gap: 12px;
  max-width: 46em;
  margin-bottom: 26px;
}

.page-about .ab-section__num {
  font-family: var(--font-mono);
  font-size: clamp(28px, 4.6vw, 52px);
  line-height: 1;
  letter-spacing: .04em;
  color: rgba(157, 179, 168, .3);
}

.page-about .ab-section__title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(23px, 3.5vw, 38px);
  line-height: 1.22;
  font-weight: 900;
  letter-spacing: -.015em;
}

.page-about .ab-lead {
  margin: 0;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--moss);
}

.page-about .ab-lead a {
  color: var(--blue);
  text-decoration: none;
  border-bottom: 1px solid rgba(70, 168, 255, .45);
}

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

.page-about .ab-prose {
  max-width: 36em;
}

.page-about .ab-prose--tight {
  margin-top: 26px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
}

.page-about .ab-prose p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.8;
  color: var(--moss);
}

.page-about .ab-prose p:last-child {
  margin-bottom: 0;
}

.page-about .ab-sub {
  margin: 0 0 12px;
  font-size: clamp(17px, 2.1vw, 21px);
  line-height: 1.4;
  font-weight: 800;
  color: var(--paper);
}

/* ---------- 图片 ---------- */
.page-about .ab-figure {
  margin: 0 0 26px;
  border: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(12, 58, 43, .5), rgba(6, 17, 12, .65));
  box-shadow: var(--ab-shadow);
  overflow: hidden;
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  opacity: .84;
}

.page-about .ab-figure--wide img {
  aspect-ratio: 16 / 9;
}

.page-about .ab-figure--tall img {
  aspect-ratio: 3 / 2;
}

.page-about .ab-figure__cap {
  padding: 11px 14px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  line-height: 1.6;
  letter-spacing: .02em;
  color: var(--moss);
}

/* ---------- 标签树 ---------- */
.page-about .ab-tree {
  display: grid;
  gap: 10px;
  margin-bottom: 26px;
}

.page-about .ab-tree__head {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  background: linear-gradient(120deg, rgba(16, 50, 58, .7), rgba(6, 17, 12, .3));
  cursor: pointer;
  list-style: none;
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

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

.page-about .ab-tree__head::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--yellow);
}

.page-about .ab-tree__branch[open] .ab-tree__head::after {
  content: "\2212";
}

.page-about .ab-tree__head:hover,
.page-about .ab-tree__head:focus-visible {
  border-color: var(--line-strong);
  background: linear-gradient(120deg, rgba(16, 50, 58, .9), rgba(6, 17, 12, .4));
}

.page-about .ab-tree__mark {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--yellow);
}

.page-about .ab-tree__name {
  font-size: 16px;
  font-weight: 700;
}

.page-about .ab-tree__count {
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--moss-dim);
}

.page-about .ab-tree__leafs {
  margin: 0;
  padding: 14px 16px 16px;
  list-style: none;
  border: 1px solid var(--line);
  border-top: 0;
  background: rgba(6, 17, 12, .35);
}

/* ---------- 指标卡 ---------- */
.page-about .ab-metrics {
  display: grid;
  gap: 14px;
  grid-template-columns: 1fr;
}

.page-about .ab-metric {
  position: relative;
  padding: 18px 18px 16px;
  border: 1px solid var(--line);
  background: linear-gradient(160deg, rgba(16, 50, 58, .55), rgba(6, 17, 12, .25));
  box-shadow: var(--ab-shadow);
  transition: border-color var(--dur) var(--ease), transform var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .ab-metric::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: var(--pitch);
  transition: background-color var(--dur) var(--ease);
}

.page-about .ab-metric:hover,
.page-about .ab-metric:focus-visible,
.page-about .ab-metric:focus-within {
  border-color: var(--line-strong);
  transform: translateY(-2px);
}

.page-about .ab-metric:hover::before,
.page-about .ab-metric:focus-visible::before {
  background: var(--yellow);
}

.page-about .ab-metric__rank {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--yellow);
}

.page-about .ab-metric__name {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 800;
}

.page-about .ab-metric__value {
  margin: 0 0 12px;
  font-family: var(--font-mono);
}

.page-about .ab-metric__value .metric {
  font-size: clamp(26px, 4vw, 40px);
  letter-spacing: -.02em;
}

.page-about .ab-metric__value em {
  font-size: 13px;
  font-style: normal;
  letter-spacing: .1em;
  margin-left: 4px;
}

.page-about .ab-metric__more {
  margin: 0;
  padding-top: 12px;
  border-top: 1px dashed var(--line-strong);
  font-size: 14px;
  line-height: 1.75;
  color: var(--moss);
}

/* ---------- 分栏 ---------- */
.page-about .ab-split {
  display: grid;
  gap: 26px;
}

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

/* ---------- 团队与荣誉 ---------- */
.page-about .ab-honors {
  display: grid;
  gap: 12px;
}

.page-about .ab-honor {
  display: grid;
  gap: 4px;
  padding: 16px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--wine);
  background: rgba(16, 50, 58, .4);
}

.page-about .ab-honor__year {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .12em;
  color: var(--yellow);
}

.page-about .ab-honor__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.6;
  font-weight: 700;
}

.page-about .ab-facts {
  margin: 4px 0 0;
  border: 1px solid var(--line);
  background: rgba(6, 17, 12, .4);
}

.page-about .ab-facts__row {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
}

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

.page-about .ab-facts__row dt {
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--moss-dim);
}

.page-about .ab-facts__row dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--blue);
}

/* ---------- 时间线 ---------- */
.page-about .ab-timeline {
  position: relative;
  margin: 0;
  padding: 0 0 0 28px;
  list-style: none;
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--yellow), var(--wine) 50%, var(--blue));
  opacity: .55;
}

.page-about .ab-timeline__item {
  position: relative;
  padding: 0 0 28px 4px;
}

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

.page-about .ab-timeline__item::before {
  content: "";
  position: absolute;
  left: -25px;
  top: 5px;
  width: 11px;
  height: 11px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: var(--ink);
  transition: border-color var(--dur) var(--ease), transform var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .ab-timeline__item:hover::before,
.page-about .ab-timeline__item:focus-within::before {
  border-color: var(--yellow);
  background: var(--yellow);
  transform: scale(1.25);
}

.page-about .ab-timeline__when {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--yellow);
}

.page-about .ab-timeline__title {
  margin: 0 0 8px;
  font-size: clamp(17px, 2.1vw, 21px);
  line-height: 1.4;
  font-weight: 800;
}

.page-about .ab-timeline__text {
  margin: 0;
  max-width: 40em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--moss);
}

/* ---------- 结尾行动区 ---------- */
.page-about .ab-cta {
  display: grid;
  gap: 22px;
  padding: var(--ab-pad-y) clamp(18px, 4vw, 56px);
  background-image:
    repeating-linear-gradient(90deg, rgba(241, 246, 243, .03) 0 1px, transparent 1px 40px),
    linear-gradient(120deg, rgba(110, 27, 38, .5), rgba(6, 17, 12, .9));
}

.page-about .ab-cta__title {
  margin: 0 0 10px;
  font-size: clamp(22px, 3.2vw, 34px);
  line-height: 1.24;
  font-weight: 900;
}

.page-about .ab-cta__desc {
  margin: 0;
  max-width: 34em;
  font-size: 15px;
  line-height: 1.8;
  color: var(--moss);
}

.page-about .ab-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 平板 ---------- */
@media (min-width: 640px) {
  .page-about .ab-metrics {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 900px) {
  .page-about .ab-hero__inner {
    grid-template-columns: minmax(0, 1.05fr) minmax(300px, .95fr);
    align-items: end;
    gap: clamp(32px, 5vw, 64px);
  }

  .page-about .ab-split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
    gap: clamp(26px, 3vw, 48px);
  }

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

  .page-about .ab-split--flip > .ab-honors {
    order: 2;
  }

  .page-about .ab-cta {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    gap: 32px;
  }

  .page-about .ab-cta__actions {
    justify-content: flex-end;
  }
}

@media (min-width: 1024px) {
  .page-about .ab-shell {
    grid-template-columns: var(--ab-rail-w) minmax(0, 1fr);
  }

  .page-about .ab-rail {
    border-bottom: 0;
    border-right: 1px solid var(--line);
    background: linear-gradient(180deg, rgba(16, 50, 58, .55), rgba(6, 17, 12, .08));
  }

  .page-about .ab-rail__list {
    display: flex;
    flex-direction: column;
    gap: 0;
    padding: 22px 0;
    overflow: visible;
    position: sticky;
    top: calc(var(--topbar-h) + 20px);
  }

  .page-about .ab-rail__node {
    flex-direction: column;
    gap: 10px;
    padding: 16px 8px;
    border-left: 0;
    border-top: 2px solid transparent;
    text-align: center;
  }

  .page-about .ab-rail__node:hover,
  .page-about .ab-rail__node:focus-visible {
    border-left-color: transparent;
    border-top-color: var(--yellow);
  }

  .page-about .ab-rail__label {
    writing-mode: vertical-rl;
    letter-spacing: .22em;
    font-size: 12px;
    line-height: 1;
  }
}

@media (min-width: 1180px) {
  .page-about .ab-metrics {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-metric,
  .page-about .ab-timeline__item::before,
  .page-about .ab-rail__node,
  .page-about .ab-rail__num {
    transition: none;
  }

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