.page-about {
  --about-rail: 300px;
  --about-line: rgba(8, 20, 24, 0.14);
  --about-muted: rgba(8, 20, 24, 0.74);
  background: var(--bb-sand);
  color: var(--bb-ink);
  overflow-x: clip;
}

/* 面包屑 */
.page-about .about-crumb {
  padding: 20px 0 0;
}
.page-about .about-crumb a {
  color: var(--bb-foam);
  text-decoration: none;
  border-bottom: 1px solid rgba(191, 227, 232, 0.45);
}
.page-about .about-crumb a:hover {
  color: var(--bb-yellow);
  border-bottom-color: var(--bb-yellow);
}
.page-about .about-crumb li,
.page-about .about-crumb [aria-current="page"] {
  color: rgba(191, 227, 232, 0.72);
}

/* 首屏 */
.page-about .about-hero {
  position: relative;
  background:
    radial-gradient(115% 145% at 92% -12%, rgba(0, 196, 140, 0.16), transparent 58%),
    radial-gradient(95% 130% at -12% 112%, rgba(10, 74, 99, 0.85), transparent 62%),
    var(--bb-deep);
  color: var(--bb-sand);
  overflow: hidden;
}
.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -34%;
  right: -14%;
  width: 56%;
  height: 168%;
  background: linear-gradient(162deg, rgba(255, 107, 53, 0.3), rgba(255, 107, 53, 0) 62%);
  transform: rotate(9deg);
  pointer-events: none;
}
.page-about .about-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 32px;
  padding: 36px 0 64px;
}
.page-about .about-hero__title {
  font-family: var(--bb-font-zh);
  font-weight: 900;
  font-size: clamp(2rem, 6.4vw, 3.6rem);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 14px 0 20px;
  color: var(--bb-sand);
}
.page-about .about-hero__lead {
  max-width: 48ch;
  margin: 0;
  font-size: 16px;
  line-height: 1.8;
  color: var(--bb-foam);
}
.page-about .about-hero__plate {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 30px 24px 36px;
  background: linear-gradient(145deg, rgba(10, 74, 99, 0.94), rgba(5, 43, 59, 0.92));
  border-top: 2px solid var(--bb-coral);
  clip-path: polygon(0 0, 100% 5%, 100% 100%, 0 95%);
}
.page-about .about-hero__kicker {
  font-family: var(--bb-font-display);
  font-size: 13px;
  letter-spacing: 0.38em;
  text-transform: uppercase;
  color: var(--bb-yellow);
}
.page-about .about-hero__year {
  font-family: var(--bb-font-display);
  font-weight: 200;
  font-size: clamp(3.2rem, 11vw, 5rem);
  line-height: 1;
  letter-spacing: 0.04em;
  color: var(--bb-sand);
}
.page-about .about-hero__place {
  margin-top: 6px;
  font-family: var(--bb-font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  color: rgba(191, 227, 232, 0.8);
}

/* 主体分栏 */
.page-about .about-body {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  padding-bottom: 64px;
}
.page-about .about-stream {
  min-width: 0;
}

.page-about .about-chapter {
  padding: 36px 0 12px;
  border-top: 1px solid var(--about-line);
}
.page-about .about-chapter:first-child {
  border-top: none;
  padding-top: 44px;
}
.page-about .about-chapter__num {
  margin: 0 0 10px;
  font-family: var(--bb-font-mono);
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--bb-coral);
}
.page-about .about-chapter h2 {
  margin: 0 0 20px;
  font-family: var(--bb-font-zh);
  font-weight: 800;
  font-size: clamp(1.5rem, 4.4vw, 2.25rem);
  line-height: 1.18;
  letter-spacing: -0.01em;
}

.page-about .about-prose p {
  margin: 0 0 14px;
  font-size: 16px;
  line-height: 1.8;
  color: var(--about-muted);
}
.page-about .about-prose p:last-child {
  margin-bottom: 0;
}
.page-about .about-prose strong {
  color: var(--bb-ink);
  font-weight: 600;
}

.page-about .about-split {
  display: grid;
  gap: 24px;
}

/* 图片 */
.page-about .about-figure {
  margin: 0;
}
.page-about .about-figure__frame {
  position: relative;
  overflow: hidden;
  background: linear-gradient(150deg, var(--bb-trench), var(--bb-deep));
}
.page-about .about-figure__frame img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}
.page-about .about-figure__cap {
  margin-top: 10px;
  padding-top: 8px;
  border-top: 1px solid var(--about-line);
  font-family: var(--bb-font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: rgba(10, 74, 99, 0.82);
}
.page-about .about-figure--band {
  margin-top: 28px;
}
.page-about .about-figure--band .about-figure__frame img {
  aspect-ratio: 16 / 7;
}

/* 五级流程 */
.page-about .about-steps {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}
.page-about .about-steps > li {
  padding: 16px 16px 18px;
  background: rgba(10, 74, 99, 0.055);
  border-top: 3px solid var(--bb-trench);
  transition: background 0.18s ease, border-color 0.18s ease;
}
.page-about .about-steps > li:hover,
.page-about .about-steps > li:focus-within {
  background: rgba(255, 107, 53, 0.09);
  border-top-color: var(--bb-coral);
}
.page-about .about-steps__n {
  display: block;
  margin-bottom: 8px;
  font-family: var(--bb-font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--bb-coral);
}
.page-about .about-steps h3 {
  margin: 0 0 6px;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.01em;
}
.page-about .about-steps p {
  margin: 0;
  font-size: 13px;
  line-height: 1.65;
  color: var(--about-muted);
}

.page-about .about-note {
  margin: 22px 0 0;
  padding: 16px 18px;
  background: rgba(10, 74, 99, 0.07);
  border-left: 3px solid var(--bb-coral);
  font-size: 15px;
  line-height: 1.72;
  color: var(--bb-ink);
}

/* 时间线 */
.page-about .about-timeline {
  list-style: none;
  margin: 24px 0 0;
  padding: 0 0 0 28px;
  position: relative;
}
.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 20px;
  bottom: 10px;
  width: 2px;
  background: linear-gradient(180deg, var(--bb-foam), var(--bb-coral));
}
.page-about .about-timeline > li {
  position: relative;
  padding-bottom: 30px;
}
.page-about .about-timeline > li:last-child {
  padding-bottom: 0;
}
.page-about .about-timeline > li::before {
  content: "";
  position: absolute;
  left: -28px;
  top: 12px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--bb-sand);
  border: 2px solid var(--bb-trench);
}
.page-about .about-timeline > li:last-child::before {
  background: var(--bb-coral);
  border-color: var(--bb-coral);
}
.page-about .about-timeline__year {
  display: block;
  font-family: var(--bb-font-display);
  font-weight: 300;
  font-size: clamp(2rem, 6vw, 3rem);
  line-height: 1;
  letter-spacing: 0.03em;
  color: var(--bb-trench);
}
.page-about .about-timeline > li:last-child .about-timeline__year {
  color: var(--bb-coral);
}
.page-about .about-timeline h3 {
  margin: 8px 0 8px;
  font-size: 17px;
  font-weight: 700;
}
.page-about .about-timeline p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--about-muted);
}

/* 合作矩阵 */
.page-about .about-partners {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--about-line);
  border-top: 1px solid var(--about-line);
  border-bottom: 1px solid var(--about-line);
}
.page-about .about-partners > li {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 2px 14px;
  align-items: baseline;
  padding: 20px 18px 22px;
  background: var(--bb-sand);
}
.page-about .about-partners__idx {
  grid-row: 1;
  font-family: var(--bb-font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--bb-coral);
}
.page-about .about-partners__name {
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.01em;
}
.page-about .about-partners__desc {
  grid-column: 1 / -1;
  margin: 6px 0 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--about-muted);
}

/* 服务方式 */
.page-about .about-service {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
}
.page-about .about-service > li {
  padding-top: 14px;
  border-top: 2px solid var(--bb-trench);
}
.page-about .about-service h3 {
  margin: 0 0 8px;
  font-size: 16px;
  font-weight: 700;
}
.page-about .about-service p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--about-muted);
}

/* 收尾 */
.page-about .about-next {
  margin-top: 44px;
  padding: 30px 24px;
  background:
    radial-gradient(120% 160% at 100% 0%, rgba(255, 107, 53, 0.24), transparent 60%),
    var(--bb-deep);
  color: var(--bb-sand);
  display: grid;
  gap: 22px;
}
.page-about .about-next__kicker {
  margin: 0 0 8px;
  font-family: var(--bb-font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--bb-yellow);
}
.page-about .about-next h2 {
  margin: 0;
  font-family: var(--bb-font-zh);
  font-weight: 800;
  font-size: clamp(1.35rem, 3.6vw, 1.85rem);
  line-height: 1.2;
}
.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* 右侧索引 */
.page-about .about-rail {
  padding: 32px 0 0;
  border-top: 1px solid var(--about-line);
  min-width: 0;
}
.page-about .about-rail__title {
  margin: 0 0 14px;
  font-family: var(--bb-font-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--bb-coral);
}
.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}
.page-about .about-rail__list a {
  display: block;
  padding: 9px 0;
  border-bottom: 1px solid var(--about-line);
  font-size: 14px;
  color: var(--about-muted);
  text-decoration: none;
  transition: color 0.16s ease, padding-left 0.16s ease;
}
.page-about .about-rail__list a:hover,
.page-about .about-rail__list a:focus-visible {
  color: var(--bb-coral);
  padding-left: 6px;
}
.page-about .about-rail__years {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
}
.page-about .about-rail__years a {
  font-family: var(--bb-font-mono);
  font-size: 12px;
  padding: 5px 11px;
  border: 1px solid var(--bb-trench);
  color: var(--bb-trench);
  text-decoration: none;
  transition: background 0.16s ease, color 0.16s ease;
}
.page-about .about-rail__years a:hover,
.page-about .about-rail__years a:focus-visible {
  background: var(--bb-trench);
  color: var(--bb-sand);
}
.page-about .about-rail__cta {
  margin-top: 20px;
}

/* 中屏 */
@media (min-width: 720px) {
  .page-about .about-steps {
    grid-template-columns: repeat(auto-fit, minmax(158px, 1fr));
    gap: 0;
    background: var(--about-line);
    border-top: 1px solid var(--about-line);
    border-bottom: 1px solid var(--about-line);
  }
  .page-about .about-steps > li {
    border-top-width: 3px;
    background: var(--bb-sand);
    padding: 18px 16px 20px;
  }
  .page-about .about-partners {
    grid-template-columns: repeat(3, 1fr);
  }
  .page-about .about-service {
    grid-template-columns: repeat(3, 1fr);
    gap: 26px;
  }
  .page-about .about-next {
    grid-template-columns: 1fr auto;
    align-items: center;
    padding: 36px 34px;
  }
}

/* 大屏 */
@media (min-width: 880px) {
  .page-about .about-hero__inner {
    grid-template-columns: minmax(0, 1.35fr) minmax(0, 0.65fr);
    align-items: end;
    gap: 48px;
    padding: 44px 0 84px;
  }
  .page-about .about-split {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    gap: 34px;
    align-items: start;
  }
  .page-about .about-split--flip .about-figure {
    order: -1;
  }
}

@media (min-width: 960px) {
  .page-about .about-body {
    grid-template-columns: minmax(0, 1fr) var(--about-rail);
    column-gap: clamp(32px, 5vw, 64px);
    align-items: start;
    padding-bottom: 88px;
  }
  .page-about .about-rail {
    position: sticky;
    top: calc(var(--bb-header-h) + 26px);
    border-top: none;
    border-left: 1px solid var(--about-line);
    padding: 48px 0 0 26px;
  }
  .page-about .about-chapter {
    padding: 48px 0 14px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-steps > li,
  .page-about .about-rail__list a,
  .page-about .about-rail__years a {
    transition: none;
  }
}
<<<END>>>