.page-about {
  --ab-year-shadow: 4px 4px 0 rgba(27, 42, 46, .95);
  --ab-card-shadow: 8px 8px 0 rgba(27, 42, 46, .75);
  display: block;
  background: var(--ud-ink);
  color: var(--ud-white);
  overflow-x: hidden;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  position: relative;
  isolation: isolate;
  padding: 56px 0 48px;
  border-bottom: 3px solid var(--ud-line);
  overflow: hidden;
}

.page-about .ab-hero__bg {
  position: absolute;
  inset: 0;
  z-index: -1;
}

.page-about .ab-hero__bg img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: .34;
  filter: saturate(.72);
}

.page-about .ab-hero__bg::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(7, 33, 27, .78) 0%, rgba(7, 33, 27, .9) 52%, var(--ud-ink) 100%);
}

.page-about .ab-hero__inner {
  display: grid;
  gap: 18px;
  align-content: start;
}

.page-about .ab-hero__title {
  margin: 0;
  font-size: clamp(34px, 8.2vw, 100px);
  line-height: 1.06;
  letter-spacing: -.03em;
  font-weight: 500;
  max-width: 16ch;
}

.page-about .ab-hero__accent {
  position: relative;
  color: var(--ud-cyan);
}

.page-about .ab-hero__accent::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: .04em;
  height: .08em;
  background: var(--ud-orange);
}

.page-about .ab-hero__lede {
  margin: 0;
  max-width: 60ch;
  font-size: clamp(15px, 1.5vw, 18px);
  line-height: 1.78;
  color: rgba(242, 247, 245, .84);
}

.page-about .ab-stats {
  list-style: none;
  margin: 10px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  border: 2px solid var(--ud-line);
  background: rgba(14, 49, 40, .78);
}

.page-about .ab-stats__item {
  display: grid;
  gap: 6px;
  align-content: start;
  padding: 16px 12px;
  border-left: 2px solid var(--ud-line);
}

.page-about .ab-stats__item:first-child {
  border-left: 0;
}

.page-about .ab-stats__num {
  font-size: clamp(22px, 3.6vw, 38px);
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--ud-cyan);
}

.page-about .ab-stats__key {
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--ud-steel);
}

/* ---------- 章节通用 ---------- */
.page-about .ab-what,
.page-about .ab-timeline,
.page-about .ab-source,
.page-about .ab-craft,
.page-about .ab-partners,
.page-about .ab-why,
.page-about .ab-cta {
  padding: clamp(44px, 7vw, 92px) 0;
  border-top: 2px solid var(--ud-line);
}

.page-about .ab-head {
  display: grid;
  gap: 10px;
  max-width: 760px;
  margin-bottom: clamp(26px, 3.6vw, 46px);
}

.page-about .ud-section__index {
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--ud-orange);
}

.page-about .ab-head h2 {
  margin: 0;
}

.page-about .ab-head__lede {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--ud-steel);
  max-width: 52ch;
}

/* ---------- A-01 ---------- */
.page-about .ab-what__grid {
  display: grid;
  gap: clamp(24px, 3.6vw, 48px);
}

.page-about .ab-what__text p {
  margin: 0 0 16px;
}

.page-about .ab-what__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.page-about .ab-what__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
  align-content: start;
}

.page-about .ab-what__row {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 4px 16px;
  padding: 18px 18px 20px;
  background: var(--ud-ink-2);
  border: 2px solid var(--ud-line);
  box-shadow: 6px 6px 0 rgba(27, 42, 46, .8);
  transition: border-color .24s var(--ud-ease), transform .24s var(--ud-ease);
}

.page-about .ab-what__row:hover {
  border-color: var(--ud-cyan);
  transform: translate(-2px, -2px);
}

.page-about .ab-what__num {
  grid-row: 1 / span 2;
  align-self: start;
  font-size: 13px;
  letter-spacing: .14em;
  color: var(--ud-orange);
  padding-top: 3px;
}

.page-about .ab-what__title {
  font-size: 17px;
  font-weight: 600;
  letter-spacing: .01em;
}

.page-about .ab-what__desc {
  font-size: 14px;
  line-height: 1.74;
  color: var(--ud-steel);
}

/* ---------- A-02 年份索引 ---------- */
.page-about .ab-years {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 6px;
  margin-bottom: clamp(28px, 4vw, 48px);
  -webkit-overflow-scrolling: touch;
}

.page-about .ab-years__item {
  flex: 0 0 auto;
  padding: 9px 18px;
  border: 2px solid var(--ud-line);
  color: var(--ud-steel);
  font-size: 14px;
  letter-spacing: .14em;
  text-decoration: none;
  transition: color .24s var(--ud-ease), background-color .24s var(--ud-ease), border-color .24s var(--ud-ease);
}

.page-about .ab-years__item:hover,
.page-about .ab-years__item:focus-visible {
  color: var(--ud-ink);
  background: var(--ud-cyan);
  border-color: var(--ud-cyan);
}

.page-about .ab-line {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0 0 0 32px;
  display: grid;
  gap: clamp(30px, 4vw, 54px);
}

.page-about .ab-line::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--ud-cyan), var(--ud-orange));
  opacity: .55;
}

.page-about .ab-node {
  position: relative;
  scroll-margin-top: 96px;
}

.page-about .ab-node::before {
  content: "";
  position: absolute;
  left: -32px;
  top: 12px;
  width: 12px;
  height: 12px;
  border: 2px solid var(--ud-cyan);
  background: var(--ud-ink);
}

.page-about .ab-node__year {
  font-size: clamp(46px, 12vw, 76px);
  line-height: .86;
  letter-spacing: -.03em;
  color: var(--ud-cyan);
  text-shadow: var(--ab-year-shadow);
  margin-bottom: 12px;
}

.page-about .ab-node__body {
  display: grid;
  gap: 10px;
  align-content: start;
}

.page-about .ab-node__body h3 {
  margin: 0;
}

.page-about .ab-node__tag {
  justify-self: start;
}

.page-about .ab-node__text {
  margin: 0;
  max-width: 48ch;
  font-size: 15px;
  line-height: 1.78;
  color: rgba(242, 247, 245, .78);
}

.page-about .ab-node__more {
  border: 0;
  padding: 0;
}

.page-about .ab-node__more > summary {
  cursor: pointer;
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  width: max-content;
  padding-bottom: 2px;
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--ud-cyan);
  border-bottom: 1px dashed var(--ud-cyan-45);
}

.page-about .ab-node__more > summary::-webkit-details-marker {
  display: none;
}

.page-about .ab-node__more > summary::after {
  content: "+";
  font-family: var(--ud-font-mono);
  font-size: 15px;
  line-height: 1;
}

.page-about .ab-node__more[open] > summary::after {
  content: "\2013";
}

.page-about .ab-node__more .ud-accordion__body {
  margin-top: 12px;
  padding: 14px 16px;
  max-width: 54ch;
  background: var(--ud-ink-2);
  border-left: 3px solid var(--ud-orange);
  font-size: 14px;
  line-height: 1.82;
  color: rgba(242, 247, 245, .76);
}

/* ---------- A-03 ---------- */
.page-about .ab-source__grid {
  display: grid;
  gap: clamp(24px, 3.6vw, 48px);
  align-items: center;
}

.page-about .ab-source__text p {
  margin: 0 0 16px;
  max-width: 48ch;
  font-size: 15px;
  line-height: 1.82;
  color: rgba(242, 247, 245, .8);
}

.page-about .ab-source__facts {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about .ab-source__facts li {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding: 9px 15px;
  border: 2px solid var(--ud-line);
  background: var(--ud-ink-2);
  font-size: 13px;
  color: var(--ud-steel);
}

.page-about .ab-source__facts .ud-mono {
  font-size: 17px;
  color: var(--ud-cyan);
}

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

/* ---------- A-04 ---------- */
.page-about .ab-craft__grid {
  display: grid;
  gap: clamp(26px, 3.6vw, 52px);
}

.page-about .ab-craft__routes {
  border-top: 2px solid var(--ud-line);
}

.page-about .ab-craft__row {
  display: grid;
  grid-template-columns: minmax(52px, auto) 1fr;
  gap: 4px 18px;
  padding: 18px 4px;
  border-bottom: 2px solid var(--ud-line);
  text-decoration: none;
  color: inherit;
  transition: background-color .24s var(--ud-ease), padding-left .24s var(--ud-ease);
}

.page-about .ab-craft__row:hover {
  background: var(--ud-cyan-06);
  padding-left: 14px;
}

.page-about .ab-craft__num {
  grid-row: 1 / span 2;
  align-self: start;
  padding-top: 4px;
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--ud-amber);
}

.page-about .ab-craft__name {
  font-size: 18px;
  font-weight: 600;
}

.page-about .ab-craft__desc {
  font-size: 14px;
  line-height: 1.74;
  color: var(--ud-steel);
}

.page-about .ab-craft__side {
  display: grid;
  gap: 20px;
  align-content: start;
}

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

.page-about .ab-craft__note {
  margin: 0;
  font-size: 14px;
  line-height: 1.82;
  color: rgba(242, 247, 245, .72);
  border-left: 3px solid var(--ud-cyan);
  padding-left: 16px;
}

/* ---------- A-05 ---------- */
.page-about .ab-partners__panel {
  padding: clamp(20px, 3vw, 36px);
  background: var(--ud-ink-2);
  border: 2px solid var(--ud-line);
  box-shadow: var(--ab-card-shadow);
}

.page-about .ab-partners__tabs {
  margin-bottom: 22px;
}

.page-about .ab-partners__intro {
  margin: 0 0 20px;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(242, 247, 245, .8);
}

.page-about .ab-chips {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about .ab-chips li {
  padding: 9px 16px;
  border: 2px solid var(--ud-line);
  background: rgba(7, 33, 27, .7);
  font-size: 14px;
  color: rgba(242, 247, 245, .86);
  transition: color .24s var(--ud-ease), background-color .24s var(--ud-ease), border-color .24s var(--ud-ease);
}

.page-about .ab-chips li:hover {
  color: var(--ud-cyan);
  border-color: var(--ud-cyan);
  background: var(--ud-cyan-06);
}

.page-about .ab-partners__foot {
  margin: clamp(22px, 3vw, 32px) 0 0;
  max-width: 66ch;
  font-size: 14px;
  line-height: 1.82;
  color: var(--ud-steel);
}

/* ---------- A-06 ---------- */
.page-about .ab-why__grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: clamp(14px, 2vw, 22px);
  grid-template-columns: repeat(auto-fit, minmax(228px, 1fr));
}

.page-about .ab-why__card {
  display: grid;
  gap: 8px;
  align-content: start;
  padding: 22px 20px 24px;
  border: 2px solid var(--ud-line);
  background: linear-gradient(180deg, rgba(14, 49, 40, .92), rgba(7, 33, 27, .92));
  transition: border-color .24s var(--ud-ease), transform .24s var(--ud-ease);
}

.page-about .ab-why__card:hover {
  border-color: var(--ud-cyan);
  transform: translateY(-4px);
}

.page-about .ab-why__num {
  font-size: clamp(34px, 5vw, 50px);
  line-height: 1;
  letter-spacing: -.03em;
  color: var(--ud-orange);
}

.page-about .ab-why__card h3 {
  margin: 0;
  font-size: 17px;
}

.page-about .ab-why__card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.76;
  color: var(--ud-steel);
}

.page-about .ab-why__foot {
  margin: clamp(24px, 3vw, 36px) 0 0;
  padding-top: 20px;
  border-top: 2px solid var(--ud-line);
  max-width: 72ch;
  font-size: 15px;
  line-height: 1.82;
  color: rgba(242, 247, 245, .8);
}

.page-about .ab-why__foot a {
  color: var(--ud-cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- 结尾 ---------- */
.page-about .ab-cta {
  background: linear-gradient(135deg, rgba(53, 242, 201, .1), rgba(255, 90, 43, .1));
  border-bottom: 3px solid var(--ud-line);
}

.page-about .ab-cta__inner {
  display: grid;
  gap: 16px;
  max-width: 720px;
}

.page-about .ab-cta__inner h2 {
  margin: 0;
}

.page-about .ab-cta__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(242, 247, 245, .82);
}

.page-about .ab-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 4px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .ab-hero {
    padding: 72px 0 64px;
  }

  .page-about .ab-node__year {
    margin-bottom: 16px;
  }
}

@media (min-width: 900px) {
  .page-about .ab-what__grid {
    grid-template-columns: 1.05fr .95fr;
    align-items: start;
  }

  .page-about .ab-source__grid {
    grid-template-columns: 1.1fr .9fr;
  }

  .page-about .ab-craft__grid {
    grid-template-columns: 1.15fr .85fr;
    align-items: start;
  }

  .page-about .ab-cta {
    padding-bottom: clamp(64px, 8vw, 104px);
  }
}

@media (min-width: 880px) {
  .page-about .ab-node {
    display: grid;
    grid-template-columns: minmax(180px, 300px) 1fr;
    gap: clamp(24px, 4vw, 56px);
    align-items: start;
  }

  .page-about .ab-node::before {
    top: 26px;
  }

  .page-about .ab-node__year {
    font-size: clamp(76px, 9vw, 132px);
    margin-bottom: 0;
  }
}

@media (max-width: 479px) {
  .page-about .ab-stats {
    grid-template-columns: 1fr;
  }

  .page-about .ab-stats__item {
    border-left: 0;
    border-top: 2px solid var(--ud-line);
  }

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