.page-about {
  --about-rail-w: 208px;
  color: var(--paper);
  padding-bottom: clamp(48px, 7vw, 96px);
}

/* 首屏 */
.page-about .about-hero {
  padding-block: clamp(16px, 2.6vw, 28px) clamp(34px, 5vw, 64px);
}

.page-about .hero-grid {
  display: grid;
  gap: clamp(28px, 5vw, 52px);
  margin-top: clamp(20px, 3vw, 34px);
}

.page-about .hero-copy {
  min-width: 0;
}

.page-about .hero-title {
  margin: 14px 0 0;
  font-size: clamp(34px, 6.4vw, 72px);
  line-height: 1.05;
  letter-spacing: -.02em;
  font-weight: 800;
  text-wrap: balance;
}

.page-about .hero-lede {
  max-width: 34em;
  margin: 20px 0 0;
  font-size: clamp(16px, 1.7vw, 18px);
  line-height: 1.85;
  color: rgba(242, 247, 251, .86);
}

.page-about .hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 32px;
  margin-top: 26px;
  padding-top: 18px;
  border-top: 1px solid var(--line-soft);
}

.page-about .meta-item {
  display: grid;
  gap: 5px;
}

.page-about .meta-k {
  font-size: 11px;
  letter-spacing: .14em;
  color: var(--mist);
}

.page-about .meta-v {
  font-size: 15px;
  letter-spacing: .04em;
  color: var(--paper);
}

.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 22px;
  margin-top: 28px;
}

.page-about .link-arrow {
  position: relative;
  color: var(--mist);
  font-size: 14.5px;
  text-decoration: none;
  padding-bottom: 3px;
  border-bottom: 1px solid var(--line-strong);
  transition: color .25s var(--ease), border-color .25s var(--ease);
}

.page-about .link-arrow:hover,
.page-about .link-arrow:focus-visible {
  color: var(--cyan);
  border-color: rgba(53, 240, 208, .6);
}

.page-about .hero-seal {
  position: relative;
  margin: 0;
  min-width: 0;
}

.page-about .hero-seal::before {
  content: "";
  position: absolute;
  inset: -13%;
  background:
    radial-gradient(circle at 62% 40%, rgba(123, 92, 255, .30), transparent 62%),
    radial-gradient(circle at 38% 66%, rgba(53, 240, 208, .18), transparent 60%);
  filter: blur(18px);
  pointer-events: none;
}

.page-about .hero-seal img {
  position: relative;
  z-index: 1;
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  border-radius: 14px;
  border: 1px solid var(--line);
}

.page-about .figure-cap {
  margin-top: 10px;
  font-size: 12.5px;
  line-height: 1.7;
  color: var(--mist);
}

/* 主栅格 */
.page-about .about-grid {
  display: grid;
  gap: clamp(28px, 4vw, 48px);
  padding-top: clamp(32px, 4.5vw, 56px);
  border-top: 1px solid var(--line-soft);
}

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

/* 右侧刻度索引 */
.page-about .about-rail {
  order: -1;
  min-width: 0;
}

.page-about .rail-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 10px;
}

.page-about .rail-link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding: 6px 10px;
  border: 1px solid var(--line-soft);
  border-radius: 6px;
  color: var(--mist);
  font-size: 13px;
  text-decoration: none;
  transition: color .25s var(--ease), border-color .25s var(--ease);
}

.page-about .rail-link:hover,
.page-about .rail-link:focus-visible {
  color: var(--cyan);
  border-color: rgba(53, 240, 208, .5);
}

.page-about .rail-key {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .08em;
  color: var(--cyan);
}

.page-about .rail-label {
  font-size: 13px;
}

/* 章节 */
.page-about .chapter {
  position: relative;
  padding-block: clamp(30px, 4.5vw, 56px);
  border-top: 1px solid var(--line-soft);
}

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

.page-about .chapter-no {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--cyan);
  margin: 0 0 10px;
}

.page-about .chapter-title {
  margin: 0 0 18px;
  font-size: clamp(26px, 3.6vw, 42px);
  line-height: 1.18;
  letter-spacing: -.015em;
  font-weight: 800;
  text-wrap: balance;
}

.page-about .chapter p {
  max-width: 34em;
  margin: 0 0 16px;
  font-size: 17px;
  line-height: 1.85;
  color: rgba(242, 247, 251, .84);
}

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

.page-about .chapter a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 240, 208, .35);
}

.page-about .chapter a:hover,
.page-about .chapter a:focus-visible {
  border-color: var(--cyan);
}

.page-about .pull {
  margin-top: 24px;
  padding-left: 18px;
  border-left: 2px solid var(--cyan);
  font-size: clamp(18px, 2.2vw, 22px);
  line-height: 1.55;
  font-weight: 600;
  letter-spacing: -.01em;
  color: var(--paper);
  max-width: 24em;
}

/* 三步复核 */
.page-about .steps {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
  border-radius: 10px;
  overflow: hidden;
}

.page-about .step {
  display: grid;
  gap: 8px;
  padding: 18px 20px;
  background: var(--night);
}

.page-about .step-no {
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--amber);
}

.page-about .step-body h3 {
  margin: 0 0 6px;
  font-size: 17px;
  letter-spacing: -.005em;
}

.page-about .step-body p {
  margin: 0;
  max-width: none;
  font-size: 15.5px;
  line-height: 1.78;
  color: var(--mist);
}

/* 折叠 */
.page-about .fold {
  margin-top: 26px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: rgba(12, 39, 64, .58);
}

.page-about .fold summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 16px 20px;
  font-size: 15.5px;
  font-weight: 600;
  color: var(--paper);
  cursor: pointer;
  list-style: none;
}

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

.page-about .fold summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--cyan);
}

.page-about .fold[open] summary::after {
  content: "–";
}

.page-about .fold-body {
  padding: 0 20px 20px;
}

.page-about .fold-body p {
  margin: 0 0 12px;
  max-width: none;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--mist);
}

.page-about .fold-body p:last-child {
  margin-bottom: 0;
}

/* 数据带 */
.page-about .stats {
  margin: clamp(30px, 4.5vw, 48px) 0 0 clamp(-72px, -6vw, 0px);
  padding: clamp(26px, 4vw, 44px) clamp(20px, 3vw, 40px);
  background:
    linear-gradient(118deg, rgba(12, 39, 64, .96) 0%, rgba(7, 26, 47, .72) 58%, rgba(123, 92, 255, .22) 100%);
  border: 1px solid var(--line);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 26px), 0 100%);
}

.page-about .stats-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px 20px;
}

.page-about .stat-num {
  display: block;
  font-size: clamp(26px, 3.6vw, 40px);
  line-height: 1.05;
  letter-spacing: -.01em;
  color: var(--paper);
}

.page-about .stat-num .u {
  font-size: .46em;
  color: var(--cyan);
  margin-left: 3px;
  letter-spacing: .02em;
}

.page-about .stat-label {
  display: block;
  margin-top: 9px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--mist);
}

/* 团队配图 */
.page-about .team-figure {
  margin: 28px 0 0;
}

.page-about .team-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  border-radius: 10px;
  border: 1px solid var(--line);
}

/* 服务承诺 */
.page-about .promise-list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 18px;
}

.page-about .promise-list li {
  display: grid;
  grid-template-columns: 14px minmax(0, 1fr);
  gap: 12px;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(242, 247, 251, .84);
}

.page-about .promise-list li::before {
  content: "";
  width: 8px;
  height: 8px;
  margin-top: .68em;
  border-radius: 2px;
  background: var(--mint);
  box-shadow: 0 0 10px rgba(79, 209, 165, .5);
}

.page-about .promise-list strong {
  color: var(--paper);
}

.page-about .chapter-link {
  font-size: 15.5px;
  color: var(--mist);
}

/* 里程碑 */
.page-about .milestone-visual {
  margin: 0 0 30px;
  position: relative;
}

.page-about .milestone-visual img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  border-radius: 10px;
  border: 1px solid var(--line);
}

.page-about .timeline {
  list-style: none;
  position: relative;
  margin: 0;
  padding: 0 0 0 22px;
  display: grid;
  gap: 26px;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: linear-gradient(180deg, rgba(53, 240, 208, .55), rgba(242, 247, 251, .08));
}

.page-about .tl-item {
  position: relative;
}

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: -22px;
  top: .55em;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  border: 1px solid var(--cyan);
  background: var(--deep);
  box-shadow: 0 0 0 3px rgba(53, 240, 208, .08);
}

.page-about .tl-key {
  display: block;
  font-size: clamp(22px, 3vw, 30px);
  line-height: 1.1;
  letter-spacing: -.01em;
  color: var(--paper);
}

.page-about .tl-body h3 {
  margin: 6px 0 6px;
  font-size: 17px;
  line-height: 1.5;
  letter-spacing: -.005em;
}

.page-about .tl-body p {
  margin: 0;
  max-width: 32em;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--mist);
}

/* 结尾 */
.page-about .about-coda {
  padding-block: clamp(56px, 8vw, 104px) clamp(20px, 3vw, 32px);
  border-top: 1px solid var(--line-soft);
  margin-top: clamp(32px, 5vw, 64px);
}

.page-about .coda-line {
  margin: 0;
  max-width: 18em;
  font-size: clamp(24px, 4vw, 44px);
  line-height: 1.24;
  letter-spacing: -.02em;
  font-weight: 800;
  color: var(--paper);
  text-wrap: balance;
}

.page-about .coda-sub {
  margin: 22px 0 0;
  max-width: 34em;
  font-size: 16px;
  line-height: 1.85;
  color: var(--mist);
}

.page-about .coda-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 16px;
  margin-top: 28px;
}

/* 断点 */
@media (min-width: 720px) {
  .page-about .step {
    grid-template-columns: 44px minmax(0, 1fr);
    gap: 10px 18px;
    padding: 22px 24px;
  }

  .page-about .stats-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 20px;
  }

  .page-about .tl-item {
    display: grid;
    grid-template-columns: 128px minmax(0, 1fr);
    gap: 8px 22px;
    align-items: start;
  }

  .page-about .tl-key {
    margin-top: 0;
  }

  .page-about .tl-body h3 {
    margin-top: 0;
  }
}

@media (min-width: 900px) {
  .page-about .hero-grid {
    grid-template-columns: minmax(0, 1.28fr) minmax(0, .72fr);
    align-items: center;
    gap: clamp(36px, 5vw, 64px);
  }
}

@media (min-width: 1000px) {
  .page-about .about-grid {
    grid-template-columns: minmax(0, 1fr) var(--about-rail-w);
    column-gap: clamp(44px, 5.5vw, 84px);
    align-items: start;
  }

  .page-about .about-rail {
    order: 0;
    position: sticky;
    top: 88px;
    align-self: start;
  }

  .page-about .rail-list {
    display: grid;
    gap: 0;
    padding-left: 20px;
    position: relative;
  }

  .page-about .rail-list::before {
    content: "";
    position: absolute;
    left: 0;
    top: 12px;
    bottom: 12px;
    width: 1px;
    background: linear-gradient(180deg, rgba(242, 247, 251, .26), rgba(242, 247, 251, .06));
  }

  .page-about .rail-item {
    position: relative;
    padding-block: 14px;
  }

  .page-about .rail-item::before {
    content: "";
    position: absolute;
    left: -24px;
    top: 21px;
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: var(--deep);
    border: 1px solid var(--line-strong);
    transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
  }

  .page-about .rail-item.is-in::before {
    background: var(--cyan);
    border-color: var(--cyan);
    box-shadow: 0 0 0 3px rgba(53, 240, 208, .12), 0 0 16px rgba(53, 240, 208, .5);
  }

  .page-about .rail-link {
    display: block;
    padding: 0;
    border: 0;
    border-radius: 0;
    background: none;
  }

  .page-about .rail-key {
    display: block;
    font-size: 13px;
    letter-spacing: .06em;
    color: var(--paper);
  }

  .page-about .rail-label {
    display: block;
    margin-top: 4px;
    font-size: 12px;
    line-height: 1.5;
    color: var(--mist);
  }

  .page-about .rail-link:hover .rail-label,
  .page-about .rail-link:focus-visible .rail-label {
    color: var(--cyan);
  }
}

@media (min-width: 1080px) {
  .page-about .chapter-no {
    position: absolute;
    left: -46px;
    top: .55em;
    margin: 0;
    color: var(--mist);
    letter-spacing: .22em;
    writing-mode: vertical-rl;
    transform: rotate(180deg);
  }

  .page-about .chapter:first-child .chapter-no {
    top: .55em;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .rail-item::before,
  .page-about .rail-link,
  .page-about .link-arrow {
    transition: none;
  }
}
<<<END>>>