.page-about {
  --about-cut: 18px;
  --about-track: linear-gradient(180deg, var(--c-mint), var(--c-green) 42%, var(--c-yellow) 76%, var(--c-orange));
  overflow-x: hidden;
}

.page-about *,
.page-about *::before,
.page-about *::after {
  box-sizing: border-box;
}

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

/* ---------- 序章 ---------- */

.page-about .about-lede {
  position: relative;
  padding: clamp(2.25rem, 7vw, 4.75rem) 0 clamp(2rem, 5vw, 3.5rem);
  background-color: var(--c-white);
  background-image: radial-gradient(120% 82% at 86% 2%, rgba(200, 247, 225, .92) 0%, rgba(127, 224, 176, .34) 34%, rgba(255, 255, 255, 0) 64%);
}

.page-about .lede-grid {
  display: grid;
  gap: clamp(1.75rem, 4vw, 3rem);
  margin-top: clamp(1.25rem, 3vw, 2rem);
}

.page-about .lede-copy h1 {
  font-family: var(--font-head);
  font-size: clamp(2.25rem, 8vw, 3.75rem);
  font-weight: 900;
  line-height: 1.04;
  letter-spacing: -.025em;
  color: var(--c-ink);
  margin: .5rem 0 1rem;
}

.page-about .lede-lead {
  margin: 0 0 1.25rem;
  max-width: 40em;
  font-size: clamp(1.02rem, 2.1vw, 1.15rem);
  line-height: 1.88;
  color: var(--ink-72);
}

.page-about .lede-sub {
  margin: 0 0 1.75rem;
  max-width: 36em;
  padding-left: 1rem;
  border-left: 3px solid var(--c-green);
  font-weight: 500;
  line-height: 1.85;
  color: var(--c-ink);
}

.page-about .lede-facts {
  display: flex;
  flex-wrap: wrap;
  gap: .9rem 2rem;
  margin: 0;
  padding-top: 1.35rem;
  border-top: 1px solid var(--line);
}

.page-about .lede-facts > div {
  display: flex;
  flex-direction: column;
  gap: .2rem;
}

.page-about .lede-facts dt {
  font-size: .76rem;
  letter-spacing: .1em;
  color: var(--ink-52);
}

.page-about .lede-facts dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -.01em;
  color: var(--c-green-deep);
}

.page-about .lede-figure {
  margin: 0;
}

.page-about .lede-figure img {
  width: 100%;
  aspect-ratio: 10 / 7;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 36px), calc(100% - 36px) 100%, 0 100%);
}

.page-about .lede-figure figcaption,
.page-about .team-figure figcaption,
.page-about .duty-figure figcaption {
  margin-top: .8rem;
  font-family: var(--font-mono);
  font-size: .78rem;
  line-height: 1.6;
  color: var(--ink-52);
}

/* ---------- 章节标题通用 ---------- */

.page-about .chapter-head {
  max-width: 44rem;
  margin-bottom: clamp(1.5rem, 4vw, 2.5rem);
}

.page-about .chapter-head h2 {
  margin: .5rem 0 .8rem;
  font-family: var(--font-head);
  font-size: clamp(1.6rem, 4.6vw, 2.5rem);
  font-weight: 900;
  line-height: 1.16;
  letter-spacing: -.018em;
  color: var(--c-ink);
}

.page-about .chapter-note {
  margin: 0;
  font-size: .98rem;
  line-height: 1.85;
  color: var(--ink-72);
}

.page-about .chapter-head--onDark h2 {
  color: var(--c-white);
}

.page-about .chapter-head--onDark .chapter-note {
  color: rgba(255, 255, 255, .7);
}

/* ---------- 章节 01 时间线 ---------- */

.page-about .about-lineage {
  background: var(--c-white);
}

.page-about .filter-bar {
  margin-bottom: clamp(1.5rem, 4vw, 2.25rem);
}

.page-about .lineage-status {
  flex-basis: 100%;
  margin: .4rem 0 0;
  font-size: .76rem;
  letter-spacing: .06em;
  color: var(--ink-52);
}

.page-about .lineage {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1.1rem;
}

.page-about .lineage::before {
  content: "";
  position: absolute;
  left: 4.5px;
  top: .6rem;
  bottom: .6rem;
  width: 3px;
  border-radius: 3px;
  background: var(--about-track);
}

.page-about .lineage-node {
  position: relative;
  padding-left: 1.9rem;
  display: grid;
  gap: .4rem;
}

.page-about .lineage-node::before {
  content: "";
  position: absolute;
  left: 0;
  top: 1.2rem;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--c-white);
  border: 3px solid var(--c-green);
}

.page-about .lineage-year {
  font-size: .88rem;
  font-weight: 700;
  letter-spacing: .05em;
  color: var(--c-green-deep);
}

.page-about .lineage-card {
  background: var(--c-white);
  border: 1px solid var(--line);
  border-left: 3px solid var(--c-green);
  padding: .85rem 1rem .95rem;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--about-cut)), calc(100% - var(--about-cut)) 100%, 0 100%);
  transition: border-color .22s var(--ease), box-shadow .22s var(--ease);
}

.page-about .lineage-card summary {
  display: flex;
  align-items: center;
  gap: .85rem;
  cursor: pointer;
  list-style: none;
}

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

.page-about .lineage-card summary h3 {
  flex: 1;
  margin: 0;
  font-family: var(--font-head);
  font-size: 1.02rem;
  font-weight: 800;
  line-height: 1.45;
  letter-spacing: -.012em;
  color: var(--c-ink);
}

.page-about .lineage-toggle {
  flex: none;
  width: 1.5rem;
  height: 1.5rem;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: var(--c-mist);
  color: var(--c-green-deep);
  font-family: var(--font-mono);
  font-size: .95rem;
  line-height: 1;
}

.page-about .lineage-toggle::before {
  content: "+";
}

.page-about .lineage-card[open] .lineage-toggle {
  background: var(--c-yellow);
  color: var(--c-ink);
}

.page-about .lineage-card[open] .lineage-toggle::before {
  content: "−";
}

.page-about .lineage-card p {
  margin: .75rem 0 0;
  font-size: .94rem;
  line-height: 1.85;
  color: var(--ink-72);
}

.page-about .lineage-card[open] {
  border-left-color: var(--c-yellow);
  box-shadow: var(--shadow-1);
}

/* ---------- 章节 02 数据里程碑 ---------- */

.page-about .about-metrics {
  position: relative;
  background: var(--c-night);
  color: var(--c-white);
  overflow: hidden;
}

.page-about .about-metrics::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--c-mint), var(--c-green) 34%, var(--c-yellow) 70%, var(--c-orange));
}

.page-about .metrics {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: rgba(255, 255, 255, .13);
  border: 1px solid rgba(255, 255, 255, .13);
}

.page-about .metric {
  background: var(--c-night);
  padding: clamp(1.25rem, 3vw, 1.9rem);
}

.page-about .metric-value {
  margin: 0 0 .7rem;
  display: flex;
  align-items: baseline;
  gap: .3rem;
}

.page-about .metric-num {
  font-family: var(--font-mono);
  font-size: clamp(2rem, 6.4vw, 2.85rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.03em;
  color: var(--c-mint);
}

@supports (-webkit-background-clip: text) {
  .page-about .metric-num {
    background: linear-gradient(100deg, var(--c-mint) 10%, var(--c-yellow) 92%);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
  }
}

.page-about .metric-unit {
  font-size: .92rem;
  font-weight: 600;
  color: rgba(255, 255, 255, .68);
}

.page-about .metric-label {
  margin: 0 0 .45rem;
  font-family: var(--font-head);
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: -.01em;
  color: var(--c-white);
}

.page-about .metric-desc {
  margin: 0;
  font-size: .88rem;
  line-height: 1.8;
  color: rgba(255, 255, 255, .66);
}

/* ---------- 章节 03 团队 ---------- */

.page-about .about-team {
  background: var(--c-white);
}

.page-about .team-grid {
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.75rem);
  margin-bottom: clamp(1.75rem, 4vw, 3rem);
}

.page-about .team-copy p {
  margin: 0 0 1rem;
  max-width: 40em;
  font-size: .98rem;
  line-height: 1.9;
  color: var(--ink-72);
}

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

.page-about .team-figure {
  margin: 0;
}

.page-about .team-figure img {
  width: 100%;
  aspect-ratio: 3 / 2;
  clip-path: polygon(calc(var(--about-cut)) 0, 100% 0, 100% 100%, 0 100%, 0 calc(var(--about-cut)));
}

.page-about .roles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1rem;
}

.page-about .role {
  background: var(--c-mist);
  padding: 1.3rem 1.2rem 1.45rem;
  clip-path: polygon(var(--about-cut) 0, 100% 0, 100% 100%, 0 100%, 0 var(--about-cut));
}

.page-about .role-num {
  display: block;
  margin-bottom: .65rem;
  font-size: .76rem;
  font-weight: 700;
  letter-spacing: .08em;
  color: var(--c-green-deep);
}

.page-about .role h3 {
  margin: 0 0 .5rem;
  font-family: var(--font-head);
  font-size: 1rem;
  font-weight: 800;
  line-height: 1.45;
  color: var(--c-ink);
}

.page-about .role p {
  margin: 0;
  font-size: .88rem;
  line-height: 1.82;
  color: var(--ink-72);
}

/* ---------- 章节 04 资质与责任 ---------- */

.page-about .about-duty {
  background: var(--c-mist);
}

.page-about .duty-grid {
  display: grid;
  gap: clamp(1.75rem, 4vw, 3rem);
}

.page-about .duty-copy h2 {
  margin: .5rem 0 .9rem;
  font-family: var(--font-head);
  font-size: clamp(1.6rem, 4.6vw, 2.5rem);
  font-weight: 900;
  line-height: 1.16;
  letter-spacing: -.018em;
  color: var(--c-ink);
}

.page-about .duty-lead {
  margin: 0;
  max-width: 40em;
  font-size: .98rem;
  line-height: 1.9;
  color: var(--ink-72);
}

.page-about .duty-facts {
  margin: 1.6rem 0 0;
  display: grid;
  gap: .85rem;
}

.page-about .duty-facts > div {
  display: grid;
  gap: .25rem;
  padding-bottom: .85rem;
  border-bottom: 1px solid var(--line);
}

.page-about .duty-facts dt {
  font-size: .74rem;
  letter-spacing: .1em;
  color: var(--ink-52);
}

.page-about .duty-facts dd {
  margin: 0;
  font-size: .96rem;
  font-weight: 700;
  line-height: 1.6;
  color: var(--c-ink);
}

.page-about .duty-facts dd.mono {
  font-family: var(--font-mono);
  letter-spacing: .01em;
}

.page-about .duty-note {
  margin: 1.35rem 0 0;
  max-width: 38em;
  font-size: .9rem;
  line-height: 1.85;
  color: var(--ink-72);
}

.page-about .duty-note a {
  color: var(--c-green-deep);
  font-weight: 700;
  text-decoration: none;
  border-bottom: 2px solid var(--c-yellow);
}

.page-about .duty-note a:hover {
  color: var(--c-ink);
}

.page-about .duty-figure {
  margin: 0;
}

.page-about .duty-figure img {
  width: 100%;
  aspect-ratio: 3 / 2;
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - var(--about-cut)), calc(100% - var(--about-cut)) 100%, 0 100%);
}

/* ---------- 章节 05 下一段赛道 ---------- */

.page-about .about-next {
  background: var(--c-white);
  padding-bottom: clamp(3rem, 8vw, 5.5rem);
}

.page-about .about-next .rule-band {
  display: block;
  margin-bottom: 1.6rem;
}

.page-about .about-next h2 {
  margin: .5rem 0 1rem;
  font-family: var(--font-head);
  font-size: clamp(1.6rem, 4.6vw, 2.5rem);
  font-weight: 900;
  line-height: 1.16;
  letter-spacing: -.018em;
  color: var(--c-ink);
}

.page-about .next-lead {
  margin: 0;
  max-width: 42em;
  font-size: 1rem;
  line-height: 1.9;
  color: var(--ink-72);
}

.page-about .next-list {
  list-style: none;
  margin: 1.6rem 0 2rem;
  padding: 0;
  max-width: 44rem;
  display: grid;
  gap: .9rem;
}

.page-about .next-list li {
  position: relative;
  padding-left: 1.7rem;
  font-size: .95rem;
  line-height: 1.85;
  color: var(--ink-72);
}

.page-about .next-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .82em;
  width: 1rem;
  height: 2px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--c-green), var(--c-yellow));
}

.page-about .next-actions {
  display: flex;
  flex-wrap: wrap;
  gap: .85rem;
}

/* ---------- 响应式 ---------- */

@media (min-width: 700px) {
  .page-about .lineage-node {
    grid-template-columns: 6.5rem minmax(0, 1fr);
    align-items: start;
    gap: 1.25rem;
    padding-left: 2.1rem;
  }

  .page-about .lineage-year {
    padding-top: .95rem;
  }

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

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

@media (min-width: 880px) {
  .page-about .lede-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    align-items: center;
  }

  .page-about .team-grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.02fr);
    align-items: center;
  }

  .page-about .duty-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    align-items: center;
  }
}

@media (min-width: 1060px) {
  .page-about .roles {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .metrics {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .lineage-node {
    grid-template-columns: 8rem minmax(0, 1fr);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .lineage-card {
    transition: none;
  }
}