.page-about {
  --ab-rail: 300px;
  --ab-gap: clamp(28px, 4vw, 56px);
  --ab-ink-soft: rgba(14, 21, 18, .68);
  --ab-ink-line: rgba(14, 21, 18, .14);
  background: var(--yt-ink-900);
  color: var(--yt-paper-50);
  overflow-x: clip;
  font-family: var(--yt-font-body);
}

.page-about .ab-inline-link {
  color: var(--yt-orange-500);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

.page-about .ab-inline-link:hover {
  color: var(--yt-orange-300);
}

/* ---------- 首屏 ---------- */

.page-about .ab-hero {
  position: relative;
  overflow-x: clip;
  padding-block: calc(var(--yt-header-h) + 20px) clamp(48px, 7vw, 88px);
  background:
    radial-gradient(120% 90% at 82% 0%, rgba(18, 112, 79, .55), transparent 62%),
    var(--yt-ink-900);
}

.page-about .ab-hero__shell {
  position: relative;
}

.page-about .ab-hero__crumbs {
  margin-bottom: clamp(24px, 4vw, 40px);
}

.page-about .ab-hero__split {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(32px, 5vw, 56px);
  align-items: center;
}

.page-about .ab-hero__split::before,
.page-about .ab-hero__split::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 1px;
  background: repeating-linear-gradient(90deg,
      var(--yt-steel-200) 0 2px,
      transparent 2px 14px);
  opacity: .35;
  pointer-events: none;
}

.page-about .ab-hero__split::before { top: -22px; }
.page-about .ab-hero__split::after { bottom: -22px; }

.page-about .ab-hero__title {
  margin: 14px 0 22px;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: clamp(38px, 6.4vw, 68px);
  line-height: 1.04;
  letter-spacing: -.03em;
  color: var(--yt-paper-50);
}

.page-about .ab-hero__lead {
  max-width: 46ch;
  color: rgba(244, 241, 232, .82);
}

.page-about .ab-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 30px;
}

.page-about .ab-hero__meta {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin: 38px 0 0;
  padding-top: 22px;
  border-top: 1px solid var(--yt-line-soft);
}

.page-about .ab-hero__meta-row dt {
  font-size: 12px;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--yt-steel-200);
  opacity: .85;
}

.page-about .ab-hero__meta-row dd {
  margin: 8px 0 0;
  font-family: var(--yt-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 20px;
  font-weight: 700;
  color: var(--yt-lime-400);
}

.page-about .ab-hero__figure {
  margin: 0;
  clip-path: var(--yt-cut);
  overflow: hidden;
  background: var(--yt-ink-700);
}

.page-about .ab-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  filter: saturate(.78) contrast(1.04);
}

/* ---------- 浅色阅读区 ---------- */

.page-about .ab-why,
.page-about .ab-team {
  background: var(--yt-paper-50);
  color: var(--yt-text-900);
}

.page-about .ab-why .yt-eyebrow,
.page-about .ab-team .yt-eyebrow {
  color: var(--yt-pitch-500);
}

.page-about .ab-why .yt-h2,
.page-about .ab-why .yt-h3,
.page-about .ab-why .yt-lead,
.page-about .ab-team .yt-h2,
.page-about .ab-team .yt-h3,
.page-about .ab-team .yt-lead {
  color: var(--yt-text-900);
}

.page-about .ab-why__lead,
.page-about .ab-team .yt-lead {
  color: var(--ab-ink-soft);
}

.page-about .ab-why__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(32px, 5vw, 60px);
  margin-top: clamp(32px, 5vw, 52px);
}

.page-about .ab-why__body {
  color: var(--yt-text-900);
  max-width: 68ch;
}

.page-about .ab-why__body p {
  margin: 0 0 20px;
  font-size: 17px;
  line-height: 1.8;
  color: rgba(14, 21, 18, .82);
}

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

.page-about .ab-stats {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px;
  margin: 0;
  padding: 0;
  align-content: start;
}

.page-about .ab-stat {
  padding-top: 18px;
  border-top: 2px solid var(--yt-pitch-500);
}

.page-about .ab-stat:last-child {
  grid-column: 1 / -1;
}

.page-about .ab-stats__value {
  display: block;
  font-family: var(--yt-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(32px, 5vw, 44px);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.03em;
  color: var(--yt-pitch-500);
}

.page-about .ab-stats__label {
  display: block;
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.6;
  letter-spacing: .05em;
  color: var(--ab-ink-soft);
}

/* ---------- 城市索引 ---------- */

.page-about .ab-cities {
  background-color: var(--yt-ink-900);
  background-image: repeating-linear-gradient(45deg,
      rgba(169, 195, 214, .045) 0 1px,
      transparent 1px 14px);
  border-top: 1px solid var(--yt-line-soft);
}

.page-about .ab-cities__tabs {
  display: block;
  margin-top: clamp(32px, 5vw, 52px);
}

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

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

.page-about .ab-city {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  grid-template-areas:
    "idx name"
    "idx hint";
  gap: 2px 12px;
  width: 100%;
  padding: 16px 18px 16px 16px;
  text-align: left;
  background: transparent;
  border: 0;
  border-left: 2px solid var(--yt-line-soft);
  color: var(--yt-steel-200);
  cursor: pointer;
  font-family: inherit;
  transition: color .22s ease, background-color .22s ease, border-color .22s ease;
}

.page-about .ab-city:hover {
  color: var(--yt-paper-50);
  background: rgba(255, 255, 255, .035);
}

.page-about .ab-city:focus-visible {
  outline: 2px solid var(--yt-orange-500);
  outline-offset: 2px;
}

.page-about .ab-city__idx {
  grid-area: idx;
  align-self: center;
  font-family: var(--yt-font-mono);
  font-size: 14px;
  letter-spacing: .06em;
  color: var(--yt-orange-300);
  transition: transform .22s ease, color .22s ease;
}

.page-about .ab-city__name {
  grid-area: name;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: 22px;
  letter-spacing: -.01em;
  line-height: 1.2;
}

.page-about .ab-city__hint {
  grid-area: hint;
  font-size: 12px;
  letter-spacing: .05em;
  color: var(--yt-steel-200);
  opacity: .7;
}

.page-about .ab-city[aria-selected="true"] {
  color: var(--yt-paper-50);
  border-left-color: var(--yt-orange-500);
  background: linear-gradient(90deg, rgba(255, 90, 31, .14), transparent 72%);
}

.page-about .ab-city[aria-selected="true"] .ab-city__idx {
  color: var(--yt-orange-500);
}

.page-about .ab-city:hover .ab-city__idx {
  transform: translateX(4px);
}

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

.page-about .ab-city-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.5vw, 40px);
  padding: clamp(24px, 3.5vw, 36px) clamp(20px, 3vw, 34px);
  background: var(--yt-ink-700);
  clip-path: var(--yt-cut);
  border-top: 2px solid var(--yt-pitch-500);
}

.page-about .ab-city-panel h3 {
  margin: 12px 0 16px;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: clamp(22px, 3vw, 28px);
  line-height: 1.25;
  letter-spacing: -.02em;
  color: var(--yt-paper-50);
}

.page-about .ab-city-panel__body > p:not(.yt-eyebrow) {
  margin: 0;
  max-width: 62ch;
  font-size: 17px;
  line-height: 1.78;
  color: rgba(244, 241, 232, .84);
}

.page-about .ab-city-facts {
  margin: 24px 0 0;
  padding: 0;
  border-top: 1px solid var(--yt-line);
}

.page-about .ab-city-facts__row {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 18px;
  padding: 12px 0;
  border-bottom: 1px solid var(--yt-line-soft);
}

.page-about .ab-city-facts__row dt {
  flex: 0 0 108px;
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--yt-steel-200);
}

.page-about .ab-city-facts__row dd {
  margin: 0;
  font-size: 14px;
  color: var(--yt-lime-400);
}

.page-about .ab-city-panel__figure {
  margin: 0;
  clip-path: var(--yt-cut-sm);
  overflow: hidden;
  background: var(--yt-ink-900);
}

.page-about .ab-city-panel__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  filter: saturate(.8);
}

/* ---------- 时间线 ---------- */

.page-about .ab-line-sec {
  background: var(--yt-ink-700);
  border-top: 1px solid var(--yt-line-soft);
}

.page-about .ab-line {
  list-style: none;
  margin: clamp(32px, 5vw, 56px) 0 0;
  padding: 0;
  counter-reset: abline;
}

.page-about .ab-line__item {
  --p: 0%;
  position: relative;
  display: grid;
  grid-template-columns: 84px minmax(0, 1fr);
  gap: 18px;
  padding-block: 26px;
  border-top: 1px solid var(--yt-line-soft);
}

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

.page-about .ab-line__year {
  align-self: start;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 38px;
  padding: 8px 10px;
  font-family: var(--yt-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--yt-paper-50);
  background: var(--yt-pitch-500);
  background: color-mix(in srgb, var(--yt-orange-500) var(--p), var(--yt-pitch-500));
  clip-path: var(--yt-cut-sm);
}

.page-about .ab-line__item:nth-child(1) { --p: 0%; }
.page-about .ab-line__item:nth-child(2) { --p: 20%; }
.page-about .ab-line__item:nth-child(3) { --p: 44%; }
.page-about .ab-line__item:nth-child(4) { --p: 66%; }
.page-about .ab-line__item:nth-child(5) { --p: 86%; }
.page-about .ab-line__item:nth-child(6) { --p: 100%; }

.page-about .ab-line__text h3 {
  margin: 0 0 10px;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: clamp(19px, 2.4vw, 23px);
  letter-spacing: -.015em;
  color: var(--yt-paper-50);
}

.page-about .ab-line__text p {
  margin: 0;
  max-width: 60ch;
  font-size: 16px;
  line-height: 1.75;
  color: rgba(244, 241, 232, .76);
}

.page-about .ab-line__item.is-visible .ab-line__year {
  animation: ab-line-lit .5s ease-out both;
}

@keyframes ab-line-lit {
  0% { transform: translateX(-6px); opacity: .4; }
  100% { transform: translateX(0); opacity: 1; }
}

/* ---------- 团队 ---------- */

.page-about .ab-team__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(32px, 5vw, 56px);
  margin-top: clamp(32px, 5vw, 52px);
  align-items: start;
}

.page-about .ab-team__figure {
  margin: 0;
  clip-path: var(--yt-cut);
  overflow: hidden;
  background: var(--yt-ink-900);
}

.page-about .ab-team__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  filter: saturate(.72);
}

.page-about .ab-role {
  position: relative;
  padding: 22px 0 22px 22px;
  border-top: 1px solid var(--ab-ink-line);
}

.page-about .ab-role:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .ab-role:first-child::before {
  top: 8px;
}

.page-about .ab-role::before {
  content: "";
  position: absolute;
  left: 0;
  top: 30px;
  width: 11px;
  height: 2px;
  background: var(--yt-orange-500);
  transform: skewX(-32deg);
}

.page-about .ab-role h3 {
  margin: 0 0 10px;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: 20px;
  letter-spacing: -.01em;
  color: var(--yt-text-900);
}

.page-about .ab-role p {
  margin: 0;
  max-width: 56ch;
  font-size: 16px;
  line-height: 1.78;
  color: rgba(14, 21, 18, .78);
}

/* ---------- 发布节奏 ---------- */

.page-about .ab-rhythm {
  padding-block: clamp(56px, 8vw, 108px);
  background:
    linear-gradient(180deg, var(--yt-ink-900), var(--yt-ink-700));
  border-top: 1px solid var(--yt-line-soft);
}

.page-about .ab-rhythm__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 56px);
  align-items: center;
}

.page-about .ab-rhythm__figure {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.page-about .ab-rhythm__num {
  font-family: var(--yt-font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(76px, 15vw, 148px);
  font-weight: 700;
  line-height: .84;
  letter-spacing: -.05em;
  color: var(--yt-orange-500);
}

.page-about .ab-rhythm__unit {
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: clamp(20px, 3vw, 30px);
  color: var(--yt-lime-400);
  letter-spacing: .04em;
}

.page-about .ab-rhythm__copy h2 {
  margin: 12px 0 18px;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: clamp(26px, 4vw, 40px);
  line-height: 1.15;
  letter-spacing: -.025em;
  color: var(--yt-paper-50);
}

.page-about .ab-rhythm__copy > p:not(.yt-eyebrow) {
  margin: 0;
  max-width: 62ch;
  font-size: 17px;
  line-height: 1.78;
  color: rgba(244, 241, 232, .82);
}

.page-about .ab-rhythm__list {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-rhythm__list li {
  position: relative;
  padding-left: 22px;
  font-size: 15px;
  line-height: 1.7;
  color: rgba(244, 241, 232, .82);
}

.page-about .ab-rhythm__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 11px;
  width: 12px;
  height: 2px;
  background: var(--yt-orange-500);
}

.page-about .ab-rhythm__more {
  margin-top: 24px;
  font-size: 15px;
  color: rgba(244, 241, 232, .72);
}

/* ---------- 合作 ---------- */

.page-about .ab-partner {
  padding-block: clamp(56px, 8vw, 104px);
  background: var(--yt-ink-700);
  border-top: 1px solid var(--yt-line-soft);
}

.page-about .ab-partner__head {
  max-width: 64ch;
}

.page-about .ab-partner__head h2 {
  margin: 12px 0 18px;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: clamp(26px, 4vw, 40px);
  line-height: 1.15;
  letter-spacing: -.025em;
  color: var(--yt-paper-50);
}

.page-about .ab-partner__head .yt-lead {
  color: rgba(244, 241, 232, .78);
}

.page-about .ab-partner__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0;
  margin-top: clamp(32px, 5vw, 52px);
  border-top: 1px solid var(--yt-line);
}

.page-about .ab-offer {
  padding: 26px 0;
  border-bottom: 1px solid var(--yt-line-soft);
}

.page-about .ab-offer h3 {
  margin: 0 0 10px;
  font-family: var(--yt-font-head);
  font-weight: 800;
  font-size: 20px;
  letter-spacing: -.01em;
  color: var(--yt-lime-400);
}

.page-about .ab-offer p {
  margin: 0;
  max-width: 40ch;
  font-size: 16px;
  line-height: 1.75;
  color: rgba(244, 241, 232, .8);
}

.page-about .ab-partner__cta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: clamp(28px, 4vw, 44px);
}

/* ---------- 响应式 ---------- */

@media (min-width: 600px) {
  .page-about .ab-partner__grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .ab-offer {
    padding: 26px 24px 30px 0;
    border-bottom: 0;
    border-right: 1px solid var(--yt-line-soft);
  }

  .page-about .ab-offer:last-child {
    border-right: 0;
    padding-right: 0;
  }

  .page-about .ab-offer + .ab-offer {
    padding-left: 24px;
  }
}

@media (min-width: 720px) {
  .page-about .ab-team__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }

  .page-about .ab-team__figure {
    position: sticky;
    top: calc(var(--yt-header-h-compact) + 32px);
  }

  .page-about .ab-city-panel {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
  }

  .page-about .ab-city-panel--plain {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (min-width: 900px) {
  .page-about .ab-why__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  }

  .page-about .ab-hero__split {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }

  .page-about .ab-hero__figure {
    margin-right: calc(-1 * max(var(--yt-gutter), (100vw - var(--yt-shell)) / 2));
  }

  .page-about .ab-rhythm__grid {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
  }
}

@media (min-width: 940px) {
  .page-about .ab-cities__layout {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
  }

  .page-about .ab-cities__rail {
    position: sticky;
    top: calc(var(--yt-header-h-compact) + 32px);
  }

  .page-about .ab-line__item {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 32px;
    padding-block: 32px;
  }

  .page-about .ab-line__year {
    font-size: 15px;
    min-height: 42px;
  }
}

@media (max-width: 420px) {
  .page-about .ab-hero__meta {
    grid-template-columns: minmax(0, 1fr);
    gap: 14px;
  }

  .page-about .ab-city {
    grid-template-columns: 34px minmax(0, 1fr);
    padding: 14px 14px 14px 12px;
  }

  .page-about .ab-rhythm__figure {
    flex-wrap: wrap;
    gap: 6px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-line__item.is-visible .ab-line__year {
    animation: none;
  }

  .page-about .ab-city,
  .page-about .ab-city__idx {
    transition: none;
  }
}