.page-about {
  --about-gap: clamp(28px, 4vw, 56px);
  background: var(--ink);
  color: var(--paper);
  padding-top: calc(var(--header-h) + clamp(20px, 4vw, 48px));
  padding-bottom: clamp(56px, 9vw, 120px);
  overflow-x: clip;
}

/* 面包屑 */
.page-about .breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-bottom: clamp(20px, 3vw, 34px);
}
.page-about .breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  padding-bottom: 2px;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}
.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  color: var(--orange);
  border-color: var(--orange);
}
.page-about .breadcrumbs__sep { color: var(--line); }
.page-about .breadcrumbs__current { color: var(--paper); }

/* 页面开头 */
.page-about .page-opening {
  position: relative;
  padding-bottom: clamp(26px, 4vw, 48px);
  border-bottom: 1px solid var(--line);
}
.page-about .page-opening::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: -3px;
  width: clamp(88px, 22vw, 260px);
  height: 6px;
  background: linear-gradient(90deg, var(--orange), var(--red));
  clip-path: polygon(0 0, 100% 0, 100% 100%, 14% 100%);
}
.page-about .page-opening__title {
  max-width: 22ch;
  text-wrap: balance;
}
.page-about .page-opening__lead {
  max-width: 64ch;
}

/* 布局：侧边目录 + 主体 */
.page-about .about-layout {
  margin-top: clamp(32px, 5vw, 64px);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
}

.page-about .about-rail {
  border-left: 2px solid var(--line);
  padding-left: 18px;
}
.page-about .about-main { min-width: 0; }

.page-about .about-block + .about-block {
  margin-top: clamp(56px, 9vw, 116px);
}

.page-about .about-head { margin-bottom: clamp(24px, 3.5vw, 40px); }
.page-about .about-head .lead { max-width: 64ch; }

/* 时间轴 */
.page-about .stages {
  position: relative;
  display: grid;
  gap: clamp(40px, 6vw, 72px);
  padding-left: 34px;
}
.page-about .stages::before {
  content: "";
  position: absolute;
  left: 8px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--orange), var(--red) 45%, var(--cyan));
  opacity: 0.75;
}
.page-about .tl-node {
  position: relative;
  min-width: 0;
}
.page-about .tl-node__dot {
  position: absolute;
  left: -31px;
  top: 8px;
  width: 12px;
  height: 12px;
  border-radius: var(--radius-pill);
  background: var(--orange);
  box-shadow: 0 0 0 4px rgba(255, 90, 31, 0.16);
}
.page-about .tl-node__year {
  font-size: clamp(26px, 5vw, 40px);
  font-weight: 700;
  letter-spacing: 0.02em;
  line-height: 1.1;
  color: var(--paper);
}
.page-about .tl-node__stage { margin: 10px 0 12px; }
.page-about .tl-node__title {
  font-size: clamp(19px, 2.6vw, 24px);
  line-height: 1.35;
  margin: 0 0 10px;
  color: var(--paper);
}
.page-about .tl-node__text {
  max-width: 60ch;
  color: var(--paper);
  opacity: 0.86;
}
.page-about .tl-node__note {
  margin-top: 14px;
  font-size: 13px;
  color: var(--muted);
  letter-spacing: 0.04em;
}
.page-about .tl-node__figure {
  margin-top: 22px;
  max-width: 100%;
}

/* 栏目分工 */
.page-about .index-list.about-columns {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 32px);
}
.page-about .about-columns .index-list__item {
  padding: clamp(16px, 2vw, 22px) clamp(16px, 2vw, 24px);
  background: var(--ink-2);
  border-radius: var(--radius-md);
  border-left: 2px solid var(--line);
  transition: border-color 0.24s var(--ease), transform 0.24s var(--ease);
}
.page-about .about-columns .index-list__item:hover {
  border-left-color: var(--orange);
  transform: translateY(-2px);
}
.page-about .about-columns .index-list__num {
  display: block;
  color: var(--cyan);
  font-size: 13px;
  margin-bottom: 8px;
}
.page-about .about-columns .index-list__label {
  margin: 0 0 8px;
  font-size: clamp(18px, 2.2vw, 21px);
}
.page-about .about-columns .index-list__meta {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.75;
}
.page-about .about-crossnote {
  margin-top: clamp(24px, 3.5vw, 36px);
  max-width: 68ch;
  padding-left: 18px;
  border-left: 2px solid var(--cyan);
}

/* 数据能力 */
.page-about .about-data {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(26px, 4vw, 48px);
  align-items: start;
}
.page-about .about-data__text p { max-width: 62ch; }
.page-about .data-tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 22px 0 0;
  padding: 0;
}
.page-about .about-data__figure { margin: 0; }

/* 账号与收藏 */
.page-about .login-steps {
  list-style: none;
  margin: clamp(20px, 3vw, 30px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}
.page-about .login-steps li {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  padding: 14px 18px;
  background: var(--ink-2);
  border-radius: var(--radius-md);
  border-left: 2px solid var(--cyan);
}
.page-about .login-steps .mono {
  color: var(--cyan);
  font-size: 13px;
  letter-spacing: 0.08em;
}
.page-about .about-login__note {
  margin-top: 22px;
  max-width: 62ch;
}
.page-about .about-login__note a {
  color: var(--cyan);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* 规模数字 */
.page-about .stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.page-about .stat-grid .stat {
  background: var(--ink-2);
  border-radius: 0;
  padding: clamp(18px, 2.6vw, 28px);
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.page-about .stat-grid .stat__value {
  color: var(--orange);
  font-size: clamp(24px, 3.4vw, 34px);
  line-height: 1.1;
}
.page-about .stat-grid .stat__label {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.6;
}
.page-about .about-team {
  margin: clamp(28px, 4vw, 48px) 0 0;
}

/* 接下来 */
.page-about .next-cards {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(16px, 2.4vw, 24px);
}
.page-about .next-card {
  border-top: 2px solid var(--orange);
  min-width: 0;
}
.page-about .next-card .card__meta {
  color: var(--muted);
  line-height: 1.75;
}
.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: clamp(28px, 4vw, 42px);
}

/* 图片统一约束 */
.page-about img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--radius-md);
}
.page-about .img-frame--square img { aspect-ratio: 1 / 1; }
.page-about .tl-node__figure img,
.page-about .about-team img { aspect-ratio: 3 / 2; }

/* 中等屏幕 */
@media (min-width: 780px) {
  .page-about .index-list.about-columns { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .page-about .next-cards { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .page-about .about-data { grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr); }
  .page-about .about-team { max-width: 78%; }
}

/* 桌面：侧栏目录 + 交错时间轴 */
@media (min-width: 1024px) {
  .page-about .about-layout {
    grid-template-columns: minmax(196px, 236px) minmax(0, 1fr);
    gap: clamp(40px, 6vw, 92px);
  }
  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 28px);
    align-self: start;
  }
  .page-about .stages {
    padding-left: 0;
    gap: clamp(52px, 6vw, 92px);
  }
  .page-about .stages::before {
    left: 50%;
    transform: translateX(-50%);
  }
  .page-about .tl-node {
    width: calc(50% - 52px);
  }
  .page-about .tl-node:nth-child(odd) {
    margin-right: auto;
  }
  .page-about .tl-node:nth-child(even) {
    margin-left: auto;
  }
  .page-about .tl-node:nth-child(odd) .tl-node__dot {
    left: auto;
    right: -58px;
  }
  .page-about .tl-node:nth-child(even) .tl-node__dot {
    left: -58px;
  }
  .page-about .tl-node:nth-child(odd) .tl-node__figure { margin-left: auto; }
}

/* 动效降级 */
@media (prefers-reduced-motion: reduce) {
  .page-about .about-columns .index-list__item,
  .page-about .breadcrumbs a {
    transition: none;
  }
  .page-about .about-columns .index-list__item:hover {
    transform: none;
  }
}
<<<END>>>