.page-about {
  --ab-rail-w: 208px;
  --ab-num-size: clamp(52px, 9vw, 112px);
  --ab-num-line: 1px solid var(--c-line);
}

/* ---------- 骨架 ---------- */
.page-about .ab-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 5vw, 48px);
  padding-block: clamp(20px, 3vw, 40px) clamp(64px, 10vw, 140px);
}

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

/* ---------- 左侧索引 ---------- */
.page-about .ab-rail {
  min-width: 0;
}

.page-about .ab-index__label {
  margin: 0 0 14px;
  color: var(--c-muted);
}

.page-about .ab-index__list {
  list-style: none;
  margin: 0;
  padding: 0 0 4px;
  display: flex;
  gap: 18px;
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

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

.page-about .ab-index__link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  white-space: nowrap;
  padding: 4px 0 6px;
  text-decoration: none;
  font-size: 14px;
  color: var(--c-muted);
  border-bottom: 1px solid transparent;
  transition: color .2s ease, border-color .2s ease;
}

.page-about .ab-index__no {
  font-size: 11px;
  letter-spacing: .12em;
  color: inherit;
  opacity: .8;
}

.page-about .ab-index__link:hover {
  color: var(--c-text);
}

.page-about .ab-index__link.is-active {
  color: var(--c-cyan);
  border-bottom-color: var(--c-cyan);
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  padding-bottom: clamp(8px, 2vw, 24px);
}

.page-about .ab-hero__crumb {
  margin: 0 0 clamp(20px, 3vw, 32px);
  font-size: 13px;
}

.page-about .ab-hero__crumb .breadcrumb__list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
  color: var(--c-muted);
}

.page-about .ab-hero__crumb a {
  color: var(--c-muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .2s ease, border-color .2s ease;
}

.page-about .ab-hero__crumb a:hover {
  color: var(--c-cyan);
  border-bottom-color: var(--c-cyan);
}

.page-about .ab-hero__crumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--c-line);
}

.page-about .ab-hero__title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(38px, 6.2vw, 76px);
  line-height: 1.03;
  letter-spacing: .01em;
  margin: 14px 0 0;
  max-width: 15ch;
  overflow-wrap: break-word;
}

.page-about .ab-hero__lede {
  margin: clamp(20px, 3vw, 28px) 0 0;
  max-width: 64ch;
  font-size: clamp(16px, 1.5vw, 18px);
  line-height: 1.78;
  color: var(--c-muted);
}

/* ---------- 图片容器 ---------- */
.page-about .ab-figure {
  margin: clamp(30px, 5vw, 52px) 0 0;
}

.page-about .ab-figure__media {
  position: relative;
  overflow: hidden;
  border: var(--line);
  background: var(--grad-water);
}

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

.page-about .ab-figure__media--14x9 { aspect-ratio: 14 / 9; }
.page-about .ab-figure__media--10x7 { aspect-ratio: 10 / 7; }
.page-about .ab-figure__media--3x2  { aspect-ratio: 3 / 2; }

.page-about .ab-figure__cap {
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--c-muted);
  max-width: 62ch;
}

/* ---------- 章节 ---------- */
.page-about .ab-chapter {
  padding-top: clamp(56px, 9vw, 116px);
}

.page-about .ab-num {
  display: block;
  margin: 0 0 6px;
  font-size: var(--ab-num-size);
  line-height: .88;
  letter-spacing: -.03em;
  font-weight: 500;
  color: var(--c-cyan);
  opacity: .32;
}

.page-about .ab-chapter__title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(26px, 3.2vw, 42px);
  line-height: 1.16;
  letter-spacing: .01em;
  margin: 0 0 20px;
  max-width: 20ch;
  overflow-wrap: break-word;
}

.page-about .ab-body {
  max-width: 68ch;
}

.page-about .ab-body p,
.page-about .ab-body__lead {
  margin: 0 0 18px;
  font-size: 17px;
  line-height: 1.78;
  color: var(--c-text);
}

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

.page-about .ab-body__lead {
  margin-bottom: 22px;
  color: var(--c-muted);
}

.page-about .ab-link {
  color: var(--c-cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--c-cyan-dim);
  transition: color .2s ease, border-color .2s ease;
}

.page-about .ab-link:hover {
  color: var(--c-orange);
  border-bottom-color: var(--c-orange);
}

/* ---------- 团队分工带 ---------- */
.page-about .ab-team {
  display: grid;
  gap: 1px;
  margin-top: clamp(28px, 4vw, 44px);
  background: var(--c-line);
  border: var(--line);
}

.page-about .ab-team__cell {
  background: var(--c-panel);
  padding: 26px 22px 30px;
  border-top: 2px solid var(--c-cyan);
  transition: opacity .25s ease;
}

.page-about .ab-team__cell:nth-child(2) { border-top-color: var(--c-cyan-dim); }
.page-about .ab-team__cell:nth-child(3) { border-top-color: var(--c-cyan); }

.page-about .ab-team:hover .ab-team__cell { opacity: .5; }
.page-about .ab-team .ab-team__cell:hover { opacity: 1; }

.page-about .ab-team__count {
  display: block;
  font-size: clamp(30px, 4vw, 44px);
  line-height: 1;
  color: var(--c-cyan);
}

.page-about .ab-team__role {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 19px;
  letter-spacing: .02em;
  margin: 14px 0 10px;
  color: var(--c-text);
}

.page-about .ab-team__desc {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--c-muted);
  max-width: 34ch;
}

/* ---------- 流程步骤 ---------- */
.page-about .ab-flow {
  list-style: none;
  margin: clamp(24px, 4vw, 36px) 0 0;
  padding: 0;
  border-top: var(--ab-num-line);
  max-width: 74ch;
}

.page-about .ab-step {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 18px;
  align-items: start;
  padding: 20px 0;
  border-bottom: var(--ab-num-line);
}

.page-about .ab-step__no {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  background: var(--c-panel);
  border: var(--line);
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--c-cyan);
}

.page-about .ab-step__title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 18px;
  letter-spacing: .03em;
  margin: 6px 0 8px;
  color: var(--c-text);
}

.page-about .ab-step__text {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.72;
  color: var(--c-muted);
  max-width: 58ch;
}

/* ---------- 数据带 ---------- */
.page-about .ab-stats {
  display: grid;
  gap: 1px;
  margin-top: clamp(26px, 4vw, 40px);
  background: var(--c-line);
  border: var(--line);
}

.page-about .ab-stat {
  background: var(--c-deep);
  padding: 26px 22px;
}

.page-about .ab-stat__num {
  display: block;
  font-size: clamp(30px, 4vw, 46px);
  line-height: 1;
  letter-spacing: -.01em;
  color: var(--c-cyan);
}

.page-about .ab-stat__label {
  display: block;
  margin-top: 14px;
  font-size: 12px;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--c-muted);
}

/* ---------- 下一步 ---------- */
.page-about .ab-next {
  margin-top: clamp(64px, 9vw, 120px);
  padding-top: clamp(30px, 4vw, 46px);
  border-top: var(--line);
}

.page-about .ab-next__list {
  list-style: none;
  margin: clamp(24px, 3vw, 34px) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--c-line);
  border: var(--line);
}

.page-about .ab-next__link {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  gap: 16px;
  background: var(--c-deep);
  padding: 22px 22px;
  text-decoration: none;
  transition: background-color .2s ease;
}

.page-about .ab-next__text {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 0;
}

.page-about .ab-next__label {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 19px;
  letter-spacing: .02em;
  color: var(--c-text);
}

.page-about .ab-next__hint {
  font-size: 13px;
  line-height: 1.5;
  color: var(--c-muted);
}

.page-about .ab-next__arrow {
  font-size: 16px;
  color: var(--c-cyan);
  transition: transform .2s ease, color .2s ease;
}

.page-about .ab-next__link:hover {
  background: var(--c-panel);
}

.page-about .ab-next__link:hover .ab-next__arrow {
  color: var(--c-orange);
  transform: translateX(5px);
}

/* ---------- 回到顶部 ---------- */
.page-about .ab-totop {
  position: fixed;
  right: clamp(12px, 3vw, 28px);
  bottom: clamp(14px, 3vw, 30px);
  z-index: 30;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  background: var(--c-panel);
  border: var(--line);
  color: var(--c-cyan);
  font-size: 16px;
  text-decoration: none;
  transition: color .2s ease, border-color .2s ease;
}

.page-about .ab-totop:hover {
  color: var(--c-orange);
  border-color: var(--c-orange);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .ab-stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .ab-step {
    grid-template-columns: 56px minmax(0, 1fr);
    gap: 24px;
    padding: 24px 0;
  }
}

@media (min-width: 720px) {
  .page-about .ab-team {
    grid-template-columns: 1.3fr 1fr 1.05fr;
  }
  .page-about .ab-next__list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1000px) {
  .page-about .ab-shell {
    grid-template-columns: var(--ab-rail-w) minmax(0, 1fr);
    gap: clamp(44px, 6vw, 84px);
  }

  .page-about .ab-index {
    position: sticky;
    top: 96px;
    border-left: var(--line);
    padding-left: 20px;
  }

  .page-about .ab-index__label {
    margin-bottom: 18px;
  }

  .page-about .ab-index__list {
    flex-direction: column;
    gap: 4px;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .ab-index__link {
    white-space: normal;
    width: 100%;
  }

  .page-about .ab-hero__lede {
    max-width: 58ch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-team__cell,
  .page-about .ab-next__link,
  .page-about .ab-next__arrow,
  .page-about .ab-index__link {
    transition: none;
  }
}
</main>