.page-about {
  --ab-rail-w: 210px;
  --ab-flow: clamp(22px, 3.6vw, 40px);
}

.page-about .ab-crumbs {
  padding-top: clamp(18px, 3.6vw, 32px);
}

.page-about .ab-hero {
  position: relative;
  padding: clamp(26px, 4.6vw, 54px) 0 clamp(38px, 6vw, 76px);
  background:
    radial-gradient(900px 420px at 84% -14%, rgba(31, 168, 160, .16), transparent 62%),
    radial-gradient(700px 380px at 2% 4%, rgba(108, 92, 231, .14), transparent 60%);
}

.page-about .ab-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--ab-flow);
}

.page-about .ab-hero__rail {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.page-about .ab-coord {
  margin: 0;
  font-family: var(--sk-font-mono);
  font-size: 11.5px;
  letter-spacing: .08em;
  color: var(--sk-mist);
  text-transform: uppercase;
}

.page-about .ab-rail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
  border-top: 1px solid var(--sk-line-soft);
  padding-top: 12px;
}

.page-about .ab-rail__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 7px 0;
  font-size: 13px;
  color: var(--sk-mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .25s var(--sk-ease), border-color .25s var(--sk-ease);
}

.page-about .ab-rail__link span {
  font-family: var(--sk-font-mono);
  font-size: 11px;
  color: var(--sk-teal);
  opacity: .8;
}

.page-about .ab-rail__link:hover,
.page-about .ab-rail__link:focus-visible {
  color: var(--sk-ice);
  border-bottom-color: var(--sk-teal);
}

.page-about .ab-hero__title {
  margin: 0 0 16px;
  font-size: clamp(32px, 6.4vw, 58px);
  line-height: 1.06;
  letter-spacing: .015em;
  font-weight: 900;
  color: var(--sk-ice);
}

.page-about .ab-hero__lede {
  max-width: 56ch;
}

.page-about .ab-hero__facts {
  list-style: none;
  margin: clamp(22px, 3.6vw, 32px) 0 0;
  padding: clamp(16px, 2.6vw, 22px) 0 0;
  border-top: 1px solid var(--sk-line);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(14px, 2.4vw, 22px);
}

.page-about .ab-fact__num {
  display: block;
  font-family: var(--sk-font-mono);
  font-size: clamp(26px, 3.6vw, 34px);
  line-height: 1;
  color: var(--sk-teal);
  letter-spacing: -.01em;
}

.page-about .ab-fact__plus {
  font-size: .6em;
  color: var(--sk-amber);
  margin-left: 2px;
}

.page-about .ab-fact__label {
  display: block;
  margin-top: 7px;
  font-size: 12.5px;
  color: var(--sk-mist);
}

.page-about .ab-hero__figure {
  margin: clamp(24px, 3.6vw, 34px) 0 0;
}

.page-about .ab-section {
  padding: clamp(40px, 6vw, 76px) 0;
}

.page-about .ab-section--band {
  background: linear-gradient(180deg, rgba(17, 38, 79, .58), rgba(7, 16, 38, 0) 82%);
  border-top: 1px solid var(--sk-line-soft);
  border-bottom: 1px solid var(--sk-line-soft);
}

.page-about .ab-head {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: clamp(24px, 3.6vw, 40px);
  max-width: 56ch;
}

.page-about .ab-head .sk-title {
  margin: 0;
  max-width: 26ch;
}

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

.page-about .ab-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.6vw, 36px);
}

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

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

.page-about .ab-side {
  padding: clamp(18px, 2.6vw, 26px);
  align-self: start;
}

.page-about .ab-side__title {
  margin: 0 0 14px;
  font-family: var(--sk-font-mono);
  font-size: 11.5px;
  letter-spacing: .14em;
  color: var(--sk-teal);
  text-transform: uppercase;
}

.page-about .ab-side__list {
  margin: 0 0 14px;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .ab-side__item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 9px;
  border-bottom: 1px solid var(--sk-line-soft);
}

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

.page-about .ab-side__key {
  font-size: 12.5px;
  color: var(--sk-mist);
  flex: 0 0 auto;
}

.page-about .ab-side__val {
  margin: 0;
  font-family: var(--sk-font-mono);
  font-size: 12.5px;
  color: var(--sk-ice);
  text-align: right;
}

.page-about .ab-side .sk-note {
  margin: 0;
}

.page-about .ab-method {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.6vw, 38px);
}

.page-about .ab-method__steps {
  display: grid;
  gap: 12px;
}

.page-about .ab-step {
  border: 1px solid var(--sk-line);
  border-radius: var(--sk-radius-sm);
  background: linear-gradient(180deg, rgba(17, 38, 79, .92), rgba(11, 27, 58, .86));
  overflow: hidden;
  transition: border-color .3s var(--sk-ease), transform .3s var(--sk-ease);
}

.page-about .ab-step:hover {
  border-color: rgba(31, 168, 160, .55);
}

.page-about .ab-step > summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 16px 18px;
  font-size: clamp(15px, 2.2vw, 16.5px);
  font-weight: 700;
  letter-spacing: .01em;
  color: var(--sk-ice);
}

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

.page-about .ab-step > summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--sk-font-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--sk-teal);
}

.page-about .ab-step[open] > summary::after {
  content: "–";
  color: var(--sk-amber);
}

.page-about .ab-step[open] > summary {
  border-bottom: 1px solid var(--sk-line-soft);
}

.page-about .ab-step__no {
  font-family: var(--sk-font-mono);
  font-size: 12px;
  color: var(--sk-mist);
  flex: 0 0 auto;
}

.page-about .ab-step__body {
  margin: 0;
  padding: 14px 18px 18px;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--sk-body);
}

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

.page-about .ab-team {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.6vw, 38px);
  align-items: start;
}

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

.page-about .ab-team__roles {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(146px, 1fr));
  gap: 12px;
  margin-bottom: 18px;
}

.page-about .ab-role {
  padding: 15px 16px;
  border: 1px solid var(--sk-line);
  border-radius: var(--sk-radius-sm);
  background: linear-gradient(180deg, rgba(17, 38, 79, .9), rgba(11, 27, 58, .9));
}

.page-about .ab-role__num {
  display: block;
  font-family: var(--sk-font-mono);
  font-size: 26px;
  line-height: 1;
  color: var(--sk-teal);
}

.page-about .ab-role__name {
  margin: 8px 0 6px;
  font-size: 14px;
  font-weight: 700;
  color: var(--sk-ice);
  letter-spacing: .02em;
}

.page-about .ab-role__desc {
  margin: 0;
  font-size: 13px;
  line-height: 1.75;
  color: var(--sk-mist);
}

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

.page-about .ab-timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 0 24px;
  position: relative;
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--sk-teal), rgba(108, 92, 231, .55), rgba(46, 63, 99, 0));
}

.page-about .ab-timeline > li {
  position: relative;
  padding-bottom: 12px;
}

.page-about .ab-timeline > li::before {
  content: "";
  position: absolute;
  left: -23px;
  top: 17px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--sk-ink-900);
  border: 1px solid var(--sk-teal);
  box-shadow: 0 0 0 3px rgba(31, 168, 160, .14);
}

.page-about .ab-node {
  border: 1px solid transparent;
  border-radius: var(--sk-radius-sm);
  transition: border-color .3s var(--sk-ease), background-color .3s var(--sk-ease);
}

.page-about .ab-node:hover {
  border-color: var(--sk-line);
  background: rgba(17, 38, 79, .55);
}

.page-about .ab-node > summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 14px;
  padding: 10px 12px;
}

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

.page-about .ab-node__year {
  font-family: var(--sk-font-mono);
  font-size: 12.5px;
  letter-spacing: .06em;
  color: var(--sk-amber);
  flex: 0 0 auto;
}

.page-about .ab-node__name {
  font-size: clamp(15px, 2.2vw, 17px);
  font-weight: 700;
  color: var(--sk-ice);
}

.page-about .ab-node > summary::after {
  content: "展开";
  margin-left: auto;
  font-family: var(--sk-font-mono);
  font-size: 11px;
  color: var(--sk-mist);
  letter-spacing: .08em;
}

.page-about .ab-node[open] > summary::after {
  content: "收起";
  color: var(--sk-teal);
}

.page-about .ab-node__body {
  margin: 0;
  padding: 0 12px 14px;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--sk-body);
  max-width: 66ch;
}

.page-about .ab-visual {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.6vw, 40px);
  align-items: center;
}

.page-about .ab-visual__frame {
  margin: 0;
  border: 1px solid var(--sk-line);
  border-radius: var(--sk-radius);
  overflow: hidden;
  background: var(--sk-ink-900);
}

.page-about .ab-visual__plate {
  aspect-ratio: 4 / 3;
  background:
    repeating-radial-gradient(circle at 22% 82%, rgba(31, 168, 160, .40) 0 1px, transparent 1px 24px),
    repeating-radial-gradient(circle at 84% 16%, rgba(108, 92, 231, .32) 0 1px, transparent 1px 33px),
    radial-gradient(circle at 68% 34%, rgba(245, 166, 35, .16), transparent 56%),
    linear-gradient(165deg, var(--sk-ink-800), var(--sk-ink-900));
}

.page-about .ab-visual__cap {
  padding: 14px 16px;
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--sk-mist);
  border-top: 1px solid var(--sk-line-soft);
}

.page-about .ab-visual__body .sk-title {
  margin: 10px 0 16px;
  max-width: 24ch;
}

.page-about .ab-visual__body p {
  margin: 0 0 14px;
}

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

.page-about .ab-reasons {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 2.8vw, 26px);
}

.page-about .ab-reason {
  padding: 4px 0 4px 18px;
  border-left: 2px solid var(--sk-line);
  transition: border-color .3s var(--sk-ease);
}

.page-about .ab-reason:hover {
  border-left-color: var(--sk-amber);
}

.page-about .ab-reason__title {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--sk-ice);
}

.page-about .ab-reason__text {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.85;
  color: var(--sk-body);
  max-width: 48ch;
}

.page-about .ab-next {
  padding: clamp(38px, 6vw, 70px) 0 clamp(18px, 4vw, 38px);
}

.page-about .ab-next__inner {
  border-top: 1px solid var(--sk-line);
  padding-top: clamp(26px, 4vw, 40px);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.page-about .ab-next__inner .sk-title {
  margin: 0;
  max-width: 24ch;
}

.page-about .ab-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 6px;
}

@media (min-width: 640px) {
  .page-about .ab-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .ab-reasons {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: clamp(28px, 4vw, 56px);
  }
}

@media (min-width: 900px) {
  .page-about .ab-hero__grid {
    grid-template-columns: var(--ab-rail-w) minmax(0, 1fr);
    gap: clamp(28px, 4vw, 56px);
    align-items: start;
  }

  .page-about .ab-hero__rail {
    position: sticky;
    top: 96px;
  }

  .page-about .ab-split {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, .85fr);
    gap: clamp(30px, 4.6vw, 62px);
    align-items: start;
  }

  .page-about .ab-visual {
    grid-template-columns: minmax(0, .95fr) minmax(0, 1.05fr);
  }
}

@media (min-width: 940px) {
  .page-about .ab-method {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, .85fr);
    align-items: start;
  }

  .page-about .ab-method__figure {
    position: sticky;
    top: 96px;
  }

  .page-about .ab-team {
    grid-template-columns: minmax(0, .9fr) minmax(0, 1.1fr);
    align-items: start;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-step,
  .page-about .ab-node,
  .page-about .ab-reason,
  .page-about .ab-rail__link {
    transition: none;
  }
}
<<<END>>>