.page-about {
  --about-tree-w: 236px;
  --about-gap: clamp(26px, 4vw, 60px);
  color: var(--text);
}

.page-about .about-hero {
  position: relative;
  padding: clamp(30px, 6vw, 76px) 0 clamp(26px, 4vw, 52px);
  border-bottom: 1px solid var(--line-soft);
  background:
    radial-gradient(120% 82% at 92% -10%, rgba(201, 255, 63, .12), transparent 62%),
    radial-gradient(90% 74% at -8% 110%, rgba(111, 227, 196, .09), transparent 64%);
  overflow: hidden;
}

.page-about .about-hero-inner {
  position: relative;
  z-index: 1;
}

.page-about .about-hero .eyebrow {
  display: inline-block;
  margin: 0 0 18px;
  padding: 5px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--amber);
  font-size: 12px;
  letter-spacing: .14em;
}

.page-about h1 {
  margin: 0 0 20px;
  max-width: 22ch;
  color: var(--paper);
  font-size: clamp(30px, 6.4vw, 56px);
  line-height: 1.1;
  letter-spacing: -.02em;
  font-weight: 800;
}

.page-about .hero-lead {
  margin: 0;
  max-width: 40em;
  font-size: 16px;
  line-height: 1.95;
  color: var(--text);
}

.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin: clamp(28px, 4vw, 44px) 0 0;
  padding: 0;
}

.page-about .about-stats .stat {
  padding: 14px 16px;
  border-left: 2px solid var(--lime);
  background: linear-gradient(180deg, rgba(20, 51, 42, .72), rgba(11, 30, 24, .4));
  border-radius: 0 var(--r-sm) var(--r-sm) 0;
}

.page-about .about-stats dt {
  margin: 0 0 6px;
  color: var(--text);
  font-size: 12px;
  letter-spacing: .08em;
}

.page-about .about-stats dd {
  margin: 0;
  color: var(--paper);
  font-size: 14px;
}

.page-about .about-stats .num {
  color: var(--lime);
  font-size: 26px;
  line-height: 1;
  margin-right: 4px;
  vertical-align: -2px;
}

.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
  padding-top: clamp(28px, 5vw, 64px);
  padding-bottom: clamp(50px, 8vw, 110px);
}

/* 章节树：移动端为横向滚动条，桌面端为纵向轨道 */
.page-about .about-tree {
  min-width: 0;
  order: -1;
}

.page-about .tree-title {
  margin: 0 0 10px;
  color: var(--mint);
  font-size: 12px;
  letter-spacing: .16em;
}

.page-about .tree-list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 6px;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.page-about .tree-list::-webkit-scrollbar {
  display: none;
}

.page-about .tree-item {
  flex: 0 0 auto;
}

.page-about .tree-link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text);
  font-size: 13px;
  text-decoration: none;
  white-space: nowrap;
  transition: color .24s var(--ease), border-color .24s var(--ease), background-color .24s var(--ease);
}

.page-about .tree-num {
  color: var(--amber);
  font-size: 12px;
}

.page-about .tree-link:hover,
.page-about .tree-link:focus-visible {
  color: var(--ink);
  background: var(--lime);
  border-color: var(--lime);
  outline: none;
}

.page-about .tree-link:hover .tree-num,
.page-about .tree-link:focus-visible .tree-num {
  color: var(--ink);
}

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

.page-about .chap {
  min-width: 0;
  padding: clamp(30px, 5vw, 62px) 0;
  border-top: 1px solid var(--line-soft);
  scroll-margin-top: calc(var(--rail-h) + 20px);
}

.page-about .about-article > .chap:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .chap-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: start;
  gap: 14px;
  margin-bottom: 20px;
}

.page-about .chap-num {
  color: transparent;
  -webkit-text-stroke: 1px rgba(201, 255, 63, .5);
  font-size: clamp(38px, 8vw, 68px);
  line-height: .9;
  letter-spacing: -.03em;
}

.page-about .chap-title {
  margin: 0;
  color: var(--paper);
  font-size: clamp(22px, 4.2vw, 32px);
  line-height: 1.24;
  letter-spacing: -.01em;
  font-weight: 800;
}

.page-about .chap-body {
  max-width: 38em;
}

.page-about .chap-body p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.95;
}

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

.page-about .chap-figure {
  margin: clamp(22px, 3.5vw, 34px) 0;
}

.page-about .chap-figure .figure-media {
  border-radius: var(--r-md);
  overflow: hidden;
  background: linear-gradient(140deg, var(--panel), var(--ink-2));
}

.page-about .chap-figure .figure-media img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .chap-figure .figure-caption {
  margin-top: 10px;
  color: var(--text);
  font-size: 13px;
  line-height: 1.8;
}

.page-about .range-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  margin: clamp(22px, 3.5vw, 32px) 0;
  padding: 0;
  list-style: none;
}

.page-about .range-item {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: var(--r-sm);
  background: var(--ink-2);
  transition: border-color .24s var(--ease), background-color .24s var(--ease);
}

.page-about .range-item:hover {
  border-color: var(--amber);
  background: var(--panel);
}

.page-about .range-key {
  color: var(--amber);
  font-size: 15px;
  font-weight: 700;
}

.page-about .range-desc {
  color: var(--text);
  font-size: 14px;
  line-height: 1.8;
}

.page-about .team-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  margin: clamp(20px, 3vw, 30px) 0;
}

.page-about .team-card {
  padding: 20px 20px 22px;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: linear-gradient(160deg, rgba(20, 51, 42, .8), rgba(6, 9, 10, .9));
}

.page-about .team-card .eyebrow {
  margin: 0 0 10px;
  color: var(--mint);
  font-size: 12px;
  letter-spacing: .14em;
}

.page-about .team-card .card-title {
  display: block;
  margin: 0 0 10px;
  color: var(--paper);
  font-size: 19px;
  line-height: 1.4;
}

.page-about .team-card p {
  margin: 0;
  color: var(--text);
  font-size: 14px;
  line-height: 1.85;
}

.page-about .chap-more {
  margin: clamp(20px, 3vw, 30px) 0 0;
}

.page-about .more-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding-bottom: 3px;
  border-bottom: 1px solid var(--mint);
  color: var(--mint);
  font-size: 15px;
  text-decoration: none;
  transition: color .24s var(--ease), border-color .24s var(--ease);
}

.page-about .more-link::after {
  content: "→";
  font-family: var(--mono);
  font-size: 13px;
}

.page-about .more-link:hover,
.page-about .more-link:focus-visible {
  color: var(--lime);
  border-color: var(--lime);
  outline: none;
}

.page-about .chap--end {
  border-top: 1px solid var(--line);
  padding-bottom: 0;
}

.page-about .about-cards {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  margin-top: clamp(20px, 3vw, 30px);
}

.page-about .about-card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 22px 20px;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: var(--ink-2);
  text-decoration: none;
  transition: transform .24s var(--ease), border-color .24s var(--ease), background-color .24s var(--ease);
}

.page-about .about-card .card-meta {
  color: var(--ember);
  font-size: 12px;
  letter-spacing: .1em;
}

.page-about .about-card .card-title {
  color: var(--paper);
  font-size: 19px;
  line-height: 1.35;
}

.page-about .about-card-text {
  color: var(--text);
  font-size: 14px;
  line-height: 1.8;
}

.page-about .about-card:hover,
.page-about .about-card:focus-visible {
  border-color: var(--lime);
  background: var(--panel);
  transform: translateY(-2px);
  outline: none;
}

.page-about .about-card:hover .card-title,
.page-about .about-card:focus-visible .card-title {
  color: var(--lime);
}

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

  .page-about .range-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .team-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 1024px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-tree-w) minmax(0, 1fr);
  }

  .page-about .about-tree {
    position: sticky;
    top: calc(var(--rail-h) + 28px);
    align-self: start;
    order: 0;
  }

  .page-about .tree-list {
    flex-direction: column;
    gap: 0;
    padding: 0 0 0 2px;
    overflow: visible;
    border-left: 1px solid var(--line);
  }

  .page-about .tree-item {
    flex: 0 0 auto;
  }

  .page-about .tree-link {
    position: relative;
    display: flex;
    width: 100%;
    padding: 11px 10px 11px 14px;
    border: 0;
    border-radius: 0;
    font-size: 14px;
  }

  .page-about .tree-link::before {
    content: "";
    position: absolute;
    left: -3px;
    top: 8px;
    bottom: 8px;
    width: 2px;
    background: transparent;
    transition: background-color .24s var(--ease);
  }

  .page-about .tree-link:hover,
  .page-about .tree-link:focus-visible {
    background: transparent;
    color: var(--lime);
  }

  .page-about .tree-link:hover::before,
  .page-about .tree-link:focus-visible::before {
    background: var(--lime);
  }

  .page-about .tree-link:hover .tree-num,
  .page-about .tree-link:focus-visible .tree-num {
    color: var(--amber);
  }
}

@media (min-width: 1200px) {
  .page-about .hero-lead {
    font-size: 17px;
  }

  .page-about .chap-body p {
    font-size: 17px;
  }
}