.page-about {
  --ab-line-dark: rgba(11, 27, 51, .16);
  --ab-muted-dark: rgba(11, 27, 51, .72);
  background: var(--pl-deep);
  color: var(--pl-paper);
  padding-bottom: clamp(48px, 7vw, 96px);
}

.page-about .ab-crumb {
  padding-top: clamp(18px, 3vw, 32px);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--pl-rock);
}

.page-about .ab-crumb a {
  color: var(--pl-muted);
  text-decoration: none;
}

.page-about .ab-crumb a:hover,
.page-about .ab-crumb a:focus-visible {
  color: var(--pl-cyan);
}

.page-about .ab-crumb span[aria-current="page"] {
  color: var(--pl-paper);
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  padding: clamp(26px, 5vw, 64px) 0 clamp(24px, 4vw, 46px);
}

.page-about .ab-hero__kicker {
  color: var(--pl-cyan);
  margin: 0;
}

.page-about .ab-h1 {
  font-family: var(--pl-font-display);
  font-weight: 800;
  font-size: clamp(34px, 7.2vw, 74px);
  line-height: 1.03;
  letter-spacing: -0.02em;
  margin: 14px 0 0;
  color: var(--pl-paper);
}

.page-about .ab-lede {
  max-width: 60ch;
  margin: 22px 0 0;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.78;
  color: var(--pl-muted);
}

.page-about .ab-hero__rule {
  margin-top: clamp(26px, 4vw, 44px);
  height: 1px;
  background: var(--pl-line-strong);
  position: relative;
}

.page-about .ab-hero__rule::before {
  content: "";
  position: absolute;
  left: 0;
  top: -1px;
  width: 96px;
  height: 2px;
  background: var(--pl-cyan);
}

/* ---------- 左侧索引 + 右侧正文 ---------- */
.page-about .ab-spread {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 56px);
}

.page-about .ab-index__title {
  color: var(--pl-rock);
  margin: 0 0 8px;
}

.page-about .ab-index__list {
  list-style: none;
  margin: 0;
  padding: 0 0 8px;
  display: flex;
  gap: 12px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .ab-index__link {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  white-space: nowrap;
  padding: 8px 0;
  border-top: 1px solid var(--pl-line);
  font-size: 13px;
  color: var(--pl-muted);
  text-decoration: none;
}

.page-about .ab-index__link .pl-mono {
  font-size: 11px;
  letter-spacing: .1em;
  color: var(--pl-cyan);
}

.page-about .ab-index__link:hover,
.page-about .ab-index__link:focus-visible {
  color: var(--pl-paper);
  border-top-color: var(--pl-cyan);
}

.page-about .ab-flow {
  display: flex;
  flex-direction: column;
  gap: clamp(40px, 6vw, 88px);
  min-width: 0;
}

/* ---------- 章节通用 ---------- */
.page-about .ab-sec {
  min-width: 0;
}

.page-about .ab-sheet {
  background: var(--pl-paper);
  color: var(--pl-deep);
  padding: clamp(22px, 3.6vw, 52px);
}

.page-about .ab-sec__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--pl-line);
  margin-bottom: clamp(18px, 2.6vw, 28px);
}

.page-about .ab-sheet .ab-sec__head {
  border-top-color: var(--ab-line-dark);
}

.page-about .ab-sec__num {
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--pl-muted);
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex: none;
}

.page-about .ab-sec__num::before {
  content: "";
  display: block;
  width: 12px;
  height: 2px;
  background: var(--pl-cyan);
}

.page-about .ab-sheet .ab-sec__num {
  color: var(--ab-muted-dark);
}

.page-about .ab-sheet .ab-sec__num::before {
  background: var(--pl-clay);
}

.page-about .ab-h2 {
  font-family: var(--pl-font-display);
  font-weight: 800;
  font-size: clamp(25px, 3.6vw, 38px);
  line-height: 1.14;
  letter-spacing: -0.015em;
  margin: 0;
  color: var(--pl-paper);
}

.page-about .ab-sheet .ab-h2 {
  color: var(--pl-deep);
}

.page-about .ab-h3 {
  font-family: var(--pl-font-body);
  font-weight: 700;
  font-size: 19px;
  line-height: 1.4;
  margin: 0 0 8px;
  color: var(--pl-paper);
}

.page-about .ab-sheet .ab-h3 {
  color: var(--pl-deep);
}

.page-about .ab-p {
  font-size: 16.5px;
  line-height: 1.78;
  margin: 0 0 14px;
  color: var(--pl-muted);
}

.page-about .ab-sheet .ab-p {
  color: var(--ab-muted-dark);
}

.page-about .ab-p--intro {
  max-width: 64ch;
  margin-bottom: clamp(20px, 3vw, 30px);
}

/* ---------- 01 场景 ---------- */
.page-about .ab-two {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 36px);
  align-items: start;
}

.page-about .ab-problems {
  list-style: none;
  margin: 0 0 22px;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .ab-problems__item {
  display: grid;
  gap: 4px;
  padding: 14px 0;
  border-bottom: 1px solid var(--pl-line);
}

.page-about .ab-problems__item:first-child {
  border-top: 1px solid var(--pl-line);
}

.page-about .ab-problems__label {
  font-family: var(--pl-font-mono);
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--pl-cyan);
}

.page-about .ab-problems__item p {
  margin: 0;
  font-size: 16px;
  line-height: 1.72;
  color: var(--pl-muted);
}

.page-about .ab-figure {
  margin: 0;
  border: 1px solid var(--pl-line);
  background: var(--pl-slate);
}

.page-about .ab-sheet .ab-figure {
  border-color: var(--ab-line-dark);
  background: #E6E1D6;
}

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

.page-about .ab-figure__caption {
  font-size: 12.5px;
  line-height: 1.6;
  letter-spacing: .02em;
  color: var(--pl-rock);
  padding: 10px 12px;
  border-top: 1px solid var(--pl-line);
}

.page-about .ab-sheet .ab-figure__caption {
  border-top-color: var(--ab-line-dark);
  color: rgba(11, 27, 51, .62);
}

.page-about .ab-figure--wide {
  margin-top: clamp(20px, 3vw, 30px);
}

.page-about .ab-figure--banner {
  margin-bottom: clamp(24px, 3.6vw, 36px);
}

/* ---------- 02 原则 ---------- */
.page-about .ab-principles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .ab-principle {
  position: relative;
  padding: clamp(16px, 2.4vw, 24px) 0;
  border-top: 1px solid var(--ab-line-dark);
}

.page-about .ab-principle:last-child {
  border-bottom: 1px solid var(--ab-line-dark);
}

.page-about .ab-principle__no {
  display: inline-block;
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--pl-clay);
  margin-bottom: 6px;
}

.page-about .ab-principle p {
  margin: 0 0 8px;
  font-size: 16px;
  line-height: 1.72;
  color: var(--ab-muted-dark);
}

.page-about .ab-principle__eg {
  font-family: var(--pl-font-mono);
  font-size: 13px;
  line-height: 1.7;
  color: var(--pl-moss);
  border-left: 2px solid var(--pl-moss);
  padding-left: 12px;
  margin: 0;
}

/* ---------- 03 团队 ---------- */
.page-about .ab-team {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
  margin-bottom: clamp(22px, 3vw, 32px);
}

.page-about .ab-team__group {
  position: relative;
  padding: 18px 0 20px;
  border-top: 1px solid var(--pl-line);
}

.page-about .ab-team__group::before {
  content: "";
  position: absolute;
  top: -4px;
  left: 0;
  width: 8px;
  height: 8px;
  background: var(--pl-clay);
}

.page-about .ab-team__no {
  display: block;
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--pl-cyan);
  margin-bottom: 6px;
}

.page-about .ab-team__group p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.74;
  color: var(--pl-muted);
}

.page-about .ab-handoff {
  border: 1px solid var(--pl-line-strong);
  padding: 16px 18px;
  background: var(--pl-slate);
}

.page-about .ab-handoff__label {
  margin: 0 0 6px;
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--pl-orange);
}

.page-about .ab-handoff__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--pl-paper);
}

/* ---------- 04 数据 ---------- */
.page-about .ab-stats {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
  border-top: 1px solid var(--ab-line-dark);
  margin-bottom: clamp(20px, 3vw, 28px);
}

.page-about .ab-stat {
  display: grid;
  gap: 4px;
  padding: 16px 0;
  border-bottom: 1px solid var(--ab-line-dark);
}

.page-about .ab-stat__num {
  font-size: clamp(32px, 5vw, 46px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--pl-deep);
}

.page-about .ab-stat__unit {
  font-size: .42em;
  letter-spacing: .08em;
  margin-left: 4px;
  color: var(--pl-clay);
}

.page-about .ab-stat__label {
  font-size: 14px;
  line-height: 1.66;
  color: var(--ab-muted-dark);
}

.page-about .ab-data__notes {
  max-width: 66ch;
}

/* ---------- 05 时间轴 ---------- */
.page-about .ab-tl {
  position: relative;
  display: flex;
  flex-direction: column;
}

.page-about .ab-tl::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: var(--pl-line-strong);
}

.page-about .ab-tl__item {
  position: relative;
  padding-left: 30px;
  border-bottom: 1px solid var(--pl-line);
}

.page-about .ab-tl__item::before {
  content: "";
  position: absolute;
  left: 1px;
  top: 21px;
  width: 9px;
  height: 9px;
  background: var(--pl-clay);
}

.page-about .ab-tl__item--now::before {
  background: var(--pl-cyan);
  box-shadow: 0 0 0 4px rgba(63, 227, 198, .18);
}

.page-about .ab-tl__summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
  padding: 16px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .ab-tl__summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--pl-font-mono);
  font-size: 16px;
  color: var(--pl-cyan);
}

.page-about .ab-tl__item[open] .ab-tl__summary::after {
  content: "−";
}

.page-about .ab-tl__year {
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--pl-muted);
}

.page-about .ab-tl__item--now .ab-tl__year {
  color: var(--pl-cyan);
}

.page-about .ab-tl__label {
  font-family: var(--pl-font-body);
  font-weight: 700;
  font-size: 18px;
  line-height: 1.4;
  color: var(--pl-paper);
}

.page-about .ab-tl__body {
  padding: 0 0 18px;
  max-width: 62ch;
}

.page-about .ab-tl__body p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.74;
  color: var(--pl-muted);
}

.page-about .ab-tl__summary:hover .ab-tl__label,
.page-about .ab-tl__summary:focus-visible .ab-tl__label {
  color: var(--pl-cyan);
}

/* ---------- 06 分段切换 ---------- */
.page-about .ab-tabs {
  margin-top: clamp(8px, 1.6vw, 16px);
}

.page-about .ab-tabs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  border-bottom: 1px solid var(--ab-line-dark);
  padding-bottom: 10px;
}

.page-about .ab-tabs__btn {
  appearance: none;
  border: 1px solid var(--ab-line-dark);
  background: transparent;
  color: var(--ab-muted-dark);
  font-family: var(--pl-font-body);
  font-size: 14px;
  letter-spacing: .02em;
  padding: 9px 14px;
  border-radius: 0;
  cursor: pointer;
}

.page-about .ab-tabs__btn[aria-selected="true"] {
  background: var(--pl-deep);
  border-color: var(--pl-deep);
  color: var(--pl-paper);
}

.page-about .ab-tabs__btn:hover,
.page-about .ab-tabs__btn:focus-visible {
  border-color: var(--pl-deep);
  color: var(--pl-deep);
}

.page-about .ab-tabs__btn[aria-selected="true"]:hover,
.page-about .ab-tabs__btn[aria-selected="true"]:focus-visible {
  color: var(--pl-paper);
}

.page-about .ab-tabs__panel {
  padding-top: 18px;
  max-width: 64ch;
}

.page-about .ab-tabs__panel p {
  margin: 0;
  font-size: 16px;
  line-height: 1.76;
  color: var(--ab-muted-dark);
}

/* ---------- 收束 ---------- */
.page-about .ab-cta {
  border-top: 1px solid var(--pl-line-strong);
  padding-top: clamp(22px, 3.4vw, 36px);
}

.page-about .ab-h2--cta {
  max-width: 22ch;
}

.page-about .ab-p--cta {
  max-width: 56ch;
  margin-top: 12px;
}

.page-about .ab-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

/* ---------- 断点 ---------- */
@media (min-width: 700px) {
  .page-about .ab-two {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, .85fr);
  }

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

  .page-about .ab-stat {
    border-bottom: none;
    border-left: 1px solid var(--ab-line-dark);
    padding: 18px 18px 18px 0;
  }

  .page-about .ab-stat:first-child {
    border-left: none;
  }

  .page-about .ab-stat + .ab-stat {
    padding-left: 18px;
  }

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

  .page-about .ab-team__group {
    padding-right: 22px;
  }

  .page-about .ab-team__group::before {
    top: -4px;
  }

  .page-about .ab-principles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 0 24px;
  }

  .page-about .ab-principle {
    border-bottom: 1px solid var(--ab-line-dark);
  }
}

@media (min-width: 1024px) {
  .page-about .ab-spread {
    grid-template-columns: 168px minmax(0, 1fr);
    gap: clamp(32px, 4.4vw, 72px);
    align-items: start;
  }

  .page-about .ab-index {
    position: sticky;
    top: 96px;
    align-self: start;
  }

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

  .page-about .ab-index__link {
    display: flex;
    justify-content: flex-start;
    padding: 11px 0;
    border-top: 1px solid var(--pl-line);
  }

  .page-about .ab-index__link:last-child {
    border-bottom: 1px solid var(--pl-line);
  }

  .page-about .ab-tl::before {
    left: 7px;
  }

  .page-about .ab-tl__item {
    padding-left: 40px;
  }

  .page-about .ab-tl__item::before {
    left: 3px;
    top: 24px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-index__link,
  .page-about .ab-tl__summary::after {
    transition: none;
  }
}
<<<END>>>