.page-about {
  background-color: var(--ink);
  background-image:
    linear-gradient(rgba(147, 166, 192, .045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(147, 166, 192, .045) 1px, transparent 1px);
  background-size: 64px 64px;
  color: var(--paper);
  overflow-x: hidden;
}

/* ---------- 面包屑 ---------- */
.page-about .crumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--muted);
  margin-bottom: 30px;
}
.page-about .crumb a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .18s ease, border-color .18s ease;
}
.page-about .crumb a:hover,
.page-about .crumb a:focus-visible {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}
.page-about .crumb__sep {
  color: var(--line-strong);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding-top: 36px;
  padding-bottom: 72px;
}
.page-about .hero-split {
  display: grid;
  gap: 36px;
}
.page-about .hero-kicker {
  margin: 0 0 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--gold);
}
.page-about .about-hero h1 {
  margin: 0 0 22px;
  font-family: var(--font-cond);
  font-size: clamp(30px, 5.2vw, 56px);
  line-height: 1.12;
  letter-spacing: .04em;
  color: var(--paper);
  padding-left: 18px;
  border-left: 3px solid var(--gold);
}
.page-about .about-hero .lede {
  margin: 0;
  max-width: 62ch;
  font-size: 17px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .hero-nums {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .hero-num {
  background: var(--ink-2);
  padding: 18px 16px 20px;
}
.page-about .hero-num dt {
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--muted);
}
.page-about .hero-num dd {
  margin: 10px 0 0;
  font-family: var(--font-mono);
  font-size: clamp(24px, 3vw, 30px);
  letter-spacing: .04em;
  color: var(--gold-hi);
  line-height: 1;
}

/* ---------- 通用小标题 ---------- */
.page-about .sec-head {
  margin-bottom: 34px;
}
.page-about .sec-head__kicker {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--cyan);
}
.page-about .sec-head__title {
  margin: 0 0 12px;
  font-family: var(--font-cond);
  font-size: clamp(25px, 3.6vw, 40px);
  line-height: 1.2;
  letter-spacing: .03em;
  color: var(--paper);
}
.page-about .sec-head__meta {
  margin: 0;
  font-size: 13.5px;
  letter-spacing: .04em;
  color: var(--muted);
  font-family: var(--font-mono);
}

/* ---------- 分屏自述 ---------- */
.page-about .about-split {
  display: grid;
  gap: 34px;
}
.page-about .fact-bar {
  border: 1px solid var(--line);
  border-left: 3px solid var(--gold);
  background: var(--ink-2);
  padding: 20px 20px 14px;
}
.page-about .fact-bar__label {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .2em;
  color: var(--gold);
}
.page-about .fact-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .fact-list li {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  padding: 9px 0;
  border-bottom: 1px solid rgba(147, 166, 192, .16);
}
.page-about .fact-list li:last-child {
  border-bottom: 0;
}
.page-about .fact-key {
  font-size: 12.5px;
  letter-spacing: .04em;
  color: var(--muted);
}
.page-about .fact-val {
  font-family: var(--font-mono);
  font-size: 17px;
  letter-spacing: .04em;
  color: var(--gold-hi);
}

.page-about .about-toc {
  margin-top: 18px;
  border: 1px solid var(--line);
  background: rgba(18, 35, 63, .6);
  padding: 18px 20px 16px;
}
.page-about .about-toc .fact-bar__label {
  color: var(--muted);
}
.page-about .toc {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .toc li + li {
  margin-top: 2px;
}
.page-about .toc__link {
  display: block;
  padding: 7px 0 7px 14px;
  position: relative;
  font-size: 14px;
  letter-spacing: .03em;
  color: var(--paper);
  text-decoration: none;
  transition: color .18s ease;
}
.page-about .toc__link::before {
  content: "";
  position: absolute;
  left: 0;
  top: 50%;
  width: 6px;
  height: 1px;
  background: var(--muted);
  transform: translateY(-50%);
  transition: width .18s ease, background .18s ease;
}
.page-about .toc__link:hover,
.page-about .toc__link:focus-visible {
  color: var(--cyan);
}
.page-about .toc__link:hover::before,
.page-about .toc__link:focus-visible::before {
  width: 10px;
  background: var(--cyan);
}

.page-about .about-split__main p {
  max-width: 68ch;
  margin: 0 0 1em;
  font-size: 17px;
  line-height: 1.8;
  color: var(--paper);
}
.page-about .about-split__main p:last-child {
  margin-bottom: 0;
}

/* ---------- 图片容器 ---------- */
.page-about .fig-frame {
  margin: 0 0 36px;
  border: 1px solid var(--line);
  background: var(--ink-2);
  overflow: hidden;
}
.page-about .fig-frame img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}
.page-about .fig-frame__cap {
  padding: 10px 14px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--muted);
}

/* ---------- 年表 ---------- */
.page-about .about-timeline .fig-frame {
  margin-bottom: 44px;
}
.page-about .tl {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}
.page-about .tl::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 10px;
  bottom: 10px;
  width: 1px;
  background: linear-gradient(180deg, var(--gold) 0%, var(--cyan) 48%, rgba(53, 224, 214, .12) 100%);
}
.page-about .tl-node {
  position: relative;
  padding-left: 34px;
  padding-bottom: 26px;
}
.page-about .tl-node:last-child {
  padding-bottom: 0;
}
.page-about .tl-node::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 15px;
  height: 15px;
  background: var(--ink);
  border: 1px solid var(--cyan);
  transform: rotate(45deg);
  transition: background .2s ease, border-color .2s ease;
}
.page-about .tl-node:nth-child(odd)::before {
  border-color: var(--gold);
}
.page-about .tl-node:hover::before {
  background: var(--cyan);
}
.page-about .tl-card {
  border: 1px solid var(--line);
  border-left: 3px solid var(--gold);
  background: var(--ink-2);
  padding: 18px 20px;
  transition: border-color .2s ease, transform .24s ease;
}
.page-about .tl-node:nth-child(even) .tl-card {
  border-left-color: var(--cyan);
}
.page-about .tl-node:hover .tl-card {
  transform: translateX(4px);
}
.page-about .tl-card__head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}
.page-about .tl-ver {
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: .1em;
  color: var(--gold-hi);
}
.page-about .tl-when {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .1em;
  color: var(--muted);
}
.page-about .tl-card__title {
  margin: 0 0 8px;
  font-size: 18px;
  font-weight: 600;
  line-height: 1.45;
  letter-spacing: .02em;
  color: var(--paper);
}
.page-about .tl-card > p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
}
.page-about .tl-det {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}
.page-about .tl-det summary {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .08em;
  color: var(--cyan);
}
.page-about .tl-det summary::-webkit-details-marker {
  display: none;
}
.page-about .tl-det summary::before {
  content: "+";
  color: var(--gold);
  font-size: 15px;
  line-height: 1;
}
.page-about .tl-det[open] summary::before {
  content: "\2212";
}
.page-about .tl-det p {
  margin: 10px 0 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--muted);
  max-width: 68ch;
}

/* ---------- 三层目录 ---------- */
.page-about .tree-layout {
  display: grid;
  gap: 34px;
}
.page-about .tree-layout .fig-frame {
  margin-bottom: 0;
}
.page-about .lv {
  position: relative;
  border: 1px solid var(--line);
  background: var(--ink-2);
  padding: 18px 20px 20px;
}
.page-about .lv + .lv {
  margin-top: 14px;
}
.page-about .lv--1 {
  border-left: 3px solid var(--gold);
}
.page-about .lv--2 {
  border-left: 3px solid var(--cyan);
}
.page-about .lv--3 {
  border-left: 3px solid var(--magenta);
}
.page-about .lv__num {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .16em;
  color: var(--muted);
}
.page-about .lv__title {
  margin: 0 0 8px;
  font-family: var(--font-cond);
  font-size: 19px;
  letter-spacing: .04em;
  color: var(--gold-hi);
}
.page-about .lv--2 .lv__title {
  color: var(--cyan);
}
.page-about .lv--3 .lv__title {
  color: var(--magenta);
}
.page-about .lv p:last-child {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
}
.page-about .tag-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 18px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

/* ---------- 团队 ---------- */
.page-about .team-layout {
  display: grid;
  gap: 30px;
}
.page-about .team-layout .fig-frame {
  margin-bottom: 0;
}
.page-about .team-grid {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .team-col {
  position: relative;
  background: var(--ink-2);
  padding: 24px 20px 22px;
}
.page-about .team-col::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
}
.page-about .team-col--a::before {
  background: var(--gold);
}
.page-about .team-col--b::before {
  background: var(--cyan);
}
.page-about .team-col--c::before {
  background: var(--magenta);
}
.page-about .team-col__num {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  letter-spacing: .16em;
  color: var(--muted);
}
.page-about .team-col__title {
  margin: 0 0 10px;
  font-size: 18px;
  font-weight: 600;
  letter-spacing: .02em;
  color: var(--paper);
}
.page-about .team-col p:last-child {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--muted);
}

.page-about .rhythm-list {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  border-top: 1px solid var(--line-strong);
}
.page-about .rhythm-list li {
  display: grid;
  gap: 6px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}
.page-about .rhythm-list__key {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .1em;
  color: var(--gold);
}
.page-about .rhythm-list__val {
  font-size: 15.5px;
  line-height: 1.7;
  color: var(--paper);
}

/* ---------- 覆盖与协作 ---------- */
.page-about .reach-band {
  padding: 64px 0 68px;
  background: linear-gradient(118deg, var(--ink-3) 0%, var(--ink) 62%, var(--ink) 100%);
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}
.page-about .reach-head {
  margin-bottom: 38px;
}
.page-about .reach-lede {
  margin: 0;
  max-width: 60ch;
  font-size: 16px;
  line-height: 1.8;
  color: var(--muted);
}
.page-about .reach-grid {
  display: grid;
  gap: 1px;
  background: rgba(147, 166, 192, .2);
  border: 1px solid var(--line);
}
.page-about .reach-cell {
  background: rgba(10, 23, 48, .78);
  padding: 24px 20px;
}
.page-about .reach-cell__num {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.4vw, 32px);
  letter-spacing: .04em;
  line-height: 1.1;
  color: var(--cyan);
}
.page-about .reach-cell__key {
  margin: 0 0 8px;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: .03em;
  color: var(--paper);
}
.page-about .reach-cell__desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--muted);
}

/* ---------- 内容要求 ---------- */
.page-about .req-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line-strong);
}
.page-about .req-list li {
  display: grid;
  gap: 10px;
  padding: 22px 0;
  border-bottom: 1px solid var(--line);
}
.page-about .req-list__num {
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: .12em;
  color: var(--gold);
}
.page-about .req-list__body h3 {
  margin: 0 0 8px;
  font-size: 17.5px;
  font-weight: 600;
  letter-spacing: .02em;
  color: var(--paper);
}
.page-about .req-list__body p {
  margin: 0;
  max-width: 68ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--muted);
}

/* ---------- 接着看 ---------- */
.page-about .next-panel {
  display: grid;
  gap: 28px;
  border: 1px solid var(--line-strong);
  background: var(--ink-2);
  padding: 30px 26px 32px;
  border-left: 3px solid var(--gold);
}
.page-about .next-panel__title {
  margin: 0;
  font-family: var(--font-cond);
  font-size: clamp(22px, 3vw, 30px);
  line-height: 1.25;
  letter-spacing: .03em;
  color: var(--paper);
}
.page-about .next-links {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .next-links li {
  display: grid;
  gap: 4px;
  padding: 13px 0;
  border-top: 1px solid var(--line);
}
.page-about .next-links li:last-child {
  border-bottom: 1px solid var(--line);
}
.page-about .next-links a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 16px;
  letter-spacing: .03em;
  color: var(--paper);
  text-decoration: none;
  transition: color .18s ease, gap .18s ease;
}
.page-about .next-links a:hover,
.page-about .next-links a:focus-visible {
  color: var(--cyan);
  gap: 14px;
}
.page-about .next-links__hint {
  font-size: 13px;
  color: var(--muted);
  padding-left: 2px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about .lv--2 {
    margin-left: 20px;
  }
  .page-about .lv--3 {
    margin-left: 40px;
  }
  .page-about .hero-nums {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .rhythm-list li {
    grid-template-columns: 190px minmax(0, 1fr);
    gap: 20px;
    align-items: baseline;
  }
  .page-about .req-list li {
    grid-template-columns: 62px minmax(0, 1fr);
    gap: 24px;
    align-items: start;
  }
  .page-about .next-panel {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr);
    gap: 40px;
    align-items: start;
    padding: 36px 34px 38px;
  }
  .page-about .team-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .reach-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .hero-split {
    grid-template-columns: minmax(0, 1.7fr) minmax(0, 1fr);
    gap: 56px;
    align-items: end;
  }
  .page-about .about-split {
    grid-template-columns: minmax(200px, 1fr) minmax(0, 2fr);
    gap: 56px;
    align-items: start;
  }
  .page-about .about-split__side {
    position: sticky;
    top: calc(var(--head) + var(--rail) + 24px);
    align-self: start;
  }
  .page-about .tree-layout {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
    gap: 48px;
    align-items: start;
  }
  .page-about .team-layout {
    grid-template-columns: minmax(0, 1fr) minmax(0, .78fr);
    gap: 44px;
    align-items: start;
  }
  .page-about .team-layout .fig-frame {
    position: sticky;
    top: calc(var(--head) + var(--rail) + 24px);
  }
  .page-about .about-hero {
    padding-top: 44px;
    padding-bottom: 88px;
  }
  .page-about .reach-band {
    padding: 76px 0 80px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition-duration: .001ms !important;
    animation-duration: .001ms !important;
  }
  .page-about .tl-node:hover .tl-card {
    transform: none;
  }
}