.page-about {
  --about-rail-w: 152px;
  --about-edge: clamp(18px, 4vw, 44px);
  --about-gap: clamp(48px, 6vw, 86px);
  background:
    radial-gradient(96% 120% at 86% 0%, rgba(0, 212, 255, .18) 0%, rgba(0, 212, 255, 0) 60%),
    linear-gradient(180deg, #0A2540 0%, #0E3A5C 44%, #07131F 100%);
  color: var(--by-pearl);
  font-family: var(--by-font-body);
  padding-bottom: clamp(48px, 7vw, 96px);
}

.page-about a {
  color: inherit;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: clamp(24px, 4vw, 46px) var(--about-edge) clamp(28px, 5vw, 56px);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: min(46vw, 520px);
  height: 5px;
  background: var(--by-grad-signal);
  border-radius: 0 0 0 6px;
}

.page-about .about-hero__inner {
  position: relative;
  max-width: var(--by-shell);
  margin: 0 auto;
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(26px, 4vw, 52px);
  margin-top: clamp(20px, 3vw, 34px);
}

.page-about .about-hero__lead h1 {
  margin: 12px 0 0;
  font-family: var(--by-font-head);
  font-weight: 800;
  font-size: clamp(32px, 5.4vw, 64px);
  line-height: 1.1;
  letter-spacing: .02em;
  color: var(--by-sand);
  max-width: 18em;
}

.page-about .about-hero__lede {
  margin: 18px 0 0;
  max-width: 34em;
  font-size: clamp(16px, 1.35vw, 18px);
  line-height: 1.85;
  color: var(--by-pearl);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

.page-about .about-hero__figure {
  position: relative;
  margin: 0;
  border: 2px solid var(--by-line-strong);
  border-radius: var(--by-radius-l);
  overflow: hidden;
  box-shadow: var(--by-shadow-card);
  background: var(--by-grad-panel);
}

.page-about .about-hero__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-about .about-hero__figure::after {
  content: "V3.1";
  position: absolute;
  top: 14px;
  right: 14px;
  padding: 4px 12px;
  border-radius: 999px;
  background: var(--by-electric);
  color: var(--by-ink);
  font-family: var(--by-font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .1em;
}

/* ---------- 数字块 ---------- */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin-top: clamp(28px, 4vw, 46px);
}

.page-about .about-stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 18px;
  border: 2px solid var(--by-line);
  border-left: 4px solid var(--by-electric);
  border-radius: var(--by-radius-s);
  background: rgba(14, 58, 92, .55);
}

.page-about .about-stat__value {
  font-family: var(--by-font-head);
  font-weight: 800;
  font-size: clamp(26px, 3.4vw, 40px);
  line-height: 1.05;
  letter-spacing: .01em;
  color: var(--by-sand);
}

.page-about .about-stat__label {
  font-size: 13px;
  line-height: 1.5;
  letter-spacing: .04em;
  color: var(--by-electric-soft);
}

/* ---------- 主框架 ---------- */
.page-about .about-frame {
  max-width: var(--by-shell);
  margin: 0 auto;
  padding: 0 var(--about-edge);
  display: grid;
  gap: clamp(28px, 4vw, 52px);
}

/* ---------- 侧栏年度索引 ---------- */
.page-about .about-rail {
  border: 2px solid var(--by-line);
  border-radius: var(--by-radius-m);
  background: rgba(7, 19, 31, .45);
  padding: 14px 16px;
}

.page-about .about-rail__title {
  margin: 0 0 10px;
  font-family: var(--by-font-mono);
  font-size: 11px;
  letter-spacing: .18em;
  color: var(--by-electric);
}

.page-about .about-rail__list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 4px;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: thin;
}

.page-about .about-rail__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border: 1px solid transparent;
  border-radius: var(--by-radius-s);
  font-family: var(--by-font-mono);
  font-size: 14px;
  white-space: nowrap;
  text-decoration: none;
  color: var(--by-pearl);
  transition: color .2s ease, border-color .2s ease, background-color .2s ease;
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--by-electric);
  border-color: var(--by-line-strong);
  background: rgba(0, 212, 255, .09);
}

.page-about .about-rail__dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--by-electric);
  box-shadow: 0 0 8px rgba(0, 212, 255, .85);
  flex: none;
}

.page-about .about-rail__note {
  margin: 12px 0 0;
  font-size: 12px;
  line-height: 1.6;
  color: var(--by-pearl);
  opacity: .78;
}

/* ---------- 内容流 ---------- */
.page-about .about-stream {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: var(--about-gap);
}

.page-about .about-section {
  min-width: 0;
}

.page-about .about-section__head {
  margin-bottom: clamp(20px, 3vw, 30px);
}

.page-about .about-section__title {
  margin: 8px 0 0;
  font-family: var(--by-font-head);
  font-weight: 800;
  font-size: clamp(25px, 3.4vw, 40px);
  line-height: 1.18;
  letter-spacing: .02em;
  color: var(--by-sand);
}

.page-about .about-section__lede {
  margin: 12px 0 0;
  max-width: 36em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--by-pearl);
  opacity: .9;
}

.page-about .about-text {
  margin: 0;
  max-width: 36em;
  font-size: 17px;
  line-height: 1.85;
  color: var(--by-pearl);
}

/* ---------- 起点 ---------- */
.page-about .about-origin__cols {
  display: grid;
  gap: 18px;
}

.page-about .about-pillars {
  display: grid;
  gap: 16px;
  margin-top: clamp(24px, 3vw, 34px);
}

.page-about .about-pillar {
  border-top: 3px solid var(--by-electric);
}

/* ---------- 服务范围 ---------- */
.page-about .about-coverage {
  display: grid;
  gap: 26px;
}

.page-about .about-coverage__figure {
  margin: 0;
  border: 2px solid var(--by-line);
  border-radius: var(--by-radius-m);
  overflow: hidden;
  background: var(--by-grad-panel);
  box-shadow: var(--by-shadow-card);
}

.page-about .about-coverage__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 10 / 7;
  object-fit: cover;
}

.page-about .about-cities {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin: 20px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-city {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid var(--by-line);
  border-radius: var(--by-radius-s);
  background: rgba(14, 58, 92, .42);
  font-size: 15px;
  color: var(--by-pearl);
  cursor: default;
  transition: border-color .2s ease, color .2s ease, transform .2s ease;
}

.page-about .about-city:hover {
  border-color: var(--by-line-strong);
  color: var(--by-sand);
  transform: translateY(-2px);
}

.page-about .about-city__dot {
  flex: none;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--by-lake);
  box-shadow: 0 0 0 3px rgba(46, 139, 158, .22);
  transition: background-color .2s ease, box-shadow .2s ease;
}

.page-about .about-city:hover .about-city__dot {
  background: var(--by-coral);
  box-shadow: 0 0 0 4px rgba(255, 107, 74, .24);
}

/* ---------- 时间线 ---------- */
.page-about .about-timeline {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-node-item {
  position: relative;
  padding-left: 30px;
}

.page-about .about-node-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 24px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--by-deep-sea);
  border: 3px solid var(--by-electric);
  box-shadow: 0 0 12px rgba(0, 212, 255, .45);
}

.page-about .about-node-item::after {
  content: "";
  position: absolute;
  left: 7px;
  top: 44px;
  bottom: -14px;
  width: 2px;
  background: linear-gradient(180deg, rgba(0, 212, 255, .5) 0%, rgba(0, 212, 255, .05) 100%);
}

.page-about .about-node-item:last-child::after {
  display: none;
}

.page-about .about-node {
  border: 2px solid var(--by-line);
  border-radius: var(--by-radius-m);
  background: rgba(14, 58, 92, .5);
  overflow: hidden;
  transition: border-color .22s ease, background-color .22s ease;
}

.page-about .about-node[open] {
  border-color: var(--by-line-strong);
  background: rgba(14, 58, 92, .72);
}

.page-about .about-node summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 18px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-node summary:focus-visible {
  outline: 2px solid var(--by-electric);
  outline-offset: -2px;
}

.page-about .about-node__year {
  flex: none;
  font-family: var(--by-font-mono);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--by-electric);
}

.page-about .about-node__title {
  flex: 1 1 auto;
  font-family: var(--by-font-head);
  font-size: 17px;
  font-weight: 700;
  color: var(--by-sand);
}

.page-about .about-node__toggle {
  position: relative;
  flex: none;
  width: 14px;
  height: 14px;
}

.page-about .about-node__toggle::before,
.page-about .about-node__toggle::after {
  content: "";
  position: absolute;
  background: var(--by-coral);
  border-radius: 2px;
  transition: transform .25s ease;
}

.page-about .about-node__toggle::before {
  left: 0;
  top: 6px;
  width: 14px;
  height: 2px;
}

.page-about .about-node__toggle::after {
  left: 6px;
  top: 0;
  width: 2px;
  height: 14px;
}

.page-about .about-node[open] .about-node__toggle::after {
  transform: scaleY(0);
}

.page-about .about-node__body {
  padding: 0 18px 18px;
  font-size: 16px;
  line-height: 1.8;
  color: var(--by-pearl);
}

.page-about .about-node__body p {
  margin: 0;
  max-width: 34em;
}

/* ---------- 团队 ---------- */
.page-about .about-team {
  display: grid;
  gap: 26px;
}

.page-about .about-team__figure {
  margin: 0;
  border: 2px solid var(--by-line);
  border-radius: var(--by-radius-m);
  overflow: hidden;
  background: var(--by-grad-panel);
  box-shadow: var(--by-shadow-card);
}

.page-about .about-team__figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-about .about-roles {
  display: grid;
  gap: 10px;
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-role {
  padding: 14px 16px;
  border-left: 3px solid var(--by-electric-soft);
  border-radius: 0 var(--by-radius-s) var(--by-radius-s) 0;
  background: rgba(7, 19, 31, .5);
}

.page-about .about-role__name {
  display: block;
  font-family: var(--by-font-head);
  font-size: 16px;
  font-weight: 700;
  color: var(--by-electric-soft);
}

.page-about .about-role__desc {
  display: block;
  margin-top: 6px;
  font-size: 15px;
  line-height: 1.7;
  color: var(--by-pearl);
}

/* ---------- 资质 ---------- */
.page-about .about-cred {
  display: grid;
  gap: 16px;
}

.page-about .about-cred__item {
  padding: 20px;
  border: 2px solid var(--by-line);
  border-radius: var(--by-radius-m);
  background: rgba(10, 37, 64, .68);
}

.page-about .about-cred__label {
  margin: 0;
  font-family: var(--by-font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--by-electric);
}

.page-about .about-cred__value {
  margin: 10px 0 0;
  font-family: var(--by-font-head);
  font-size: clamp(18px, 2vw, 22px);
  font-weight: 800;
  line-height: 1.35;
  color: var(--by-sand);
}

.page-about .about-cred__note {
  margin: 10px 0 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--by-pearl);
  opacity: .88;
}

/* ---------- 生态 ---------- */
.page-about .about-ecosystem {
  display: grid;
  gap: 16px;
}

.page-about .about-eco {
  position: relative;
  padding: 22px 20px 20px;
  border: 2px solid var(--by-line);
  border-radius: var(--by-radius-m);
  background: rgba(14, 58, 92, .5);
  transition: transform .25s ease, border-color .25s ease, box-shadow .25s ease;
}

.page-about .about-eco:hover,
.page-about .about-eco:focus-within {
  transform: translateY(-4px);
  border-color: var(--by-line-strong);
  box-shadow: var(--by-shadow-card-hover);
}

.page-about .about-eco__tag {
  margin: 0;
  font-family: var(--by-font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--by-coral);
}

.page-about .about-eco__title {
  margin: 10px 0 0;
  font-family: var(--by-font-head);
  font-size: 21px;
  font-weight: 800;
  color: var(--by-sand);
}

.page-about .about-eco__text {
  margin: 10px 0 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--by-pearl);
}

.page-about .about-eco__more {
  margin: 14px 0 0;
  padding-top: 12px;
  border-top: 1px dashed var(--by-line);
  font-size: 13px;
  line-height: 1.6;
  letter-spacing: .03em;
  color: var(--by-electric-soft);
}

.page-about .about-eco-cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-top: 24px;
  padding: 20px 22px;
  border: 2px dashed var(--by-line);
  border-radius: var(--by-radius-m);
  background: rgba(7, 19, 31, .42);
}

.page-about .about-eco-cta__text {
  margin: 0;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.75;
  color: var(--by-pearl);
}

/* ---------- 尾部行动区 ---------- */
.page-about .about-cta {
  padding: clamp(28px, 4vw, 46px);
  border: 2px solid var(--by-line-strong);
  border-radius: var(--by-radius-l);
  background: var(--by-grad-panel);
  box-shadow: var(--by-shadow-card);
}

.page-about .about-cta__title {
  margin: 0;
  font-family: var(--by-font-head);
  font-size: clamp(23px, 3vw, 34px);
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: .02em;
  color: var(--by-sand);
}

.page-about .about-cta__text {
  margin: 14px 0 0;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--by-pearl);
}

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

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about .about-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 14px;
  }

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

  .page-about .about-origin__cols {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px 34px;
    align-items: start;
  }

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

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

@media (min-width: 880px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.04fr) minmax(0, .96fr);
    align-items: end;
  }

  .page-about .about-coverage {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    align-items: center;
    gap: 34px;
  }

  .page-about .about-team {
    grid-template-columns: minmax(0, .92fr) minmax(0, 1.08fr);
    align-items: center;
    gap: 34px;
  }
}

@media (min-width: 1040px) {
  .page-about .about-frame {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(34px, 4vw, 60px);
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--by-header-h) + 24px);
    align-self: start;
  }

  .page-about .about-rail__list {
    flex-direction: column;
    gap: 2px;
    overflow-x: visible;
    padding-bottom: 0;
  }

  .page-about .about-origin__cols > p:nth-child(2) {
    margin-top: 52px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-city,
  .page-about .about-eco,
  .page-about .about-node__toggle::before,
  .page-about .about-node__toggle::after,
  .page-about .about-rail__link {
    transition: none;
  }
}