.page-about {
  --about-rail: 168px;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
}

.page-about .about-shell {
  width: min(var(--shell), 100%);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  overflow: hidden;
  background: var(--ink);
  color: var(--paper);
}

.page-about .about-hero__slant {
  position: absolute;
  top: -25%;
  right: -10%;
  width: 70%;
  height: 150%;
  background: linear-gradient(140deg, rgba(255, 77, 28, .95) 0%, rgba(179, 33, 14, .88) 48%, rgba(27, 42, 68, 0) 92%);
  transform: skewX(-15deg);
  pointer-events: none;
}

.page-about .about-hero__inner {
  position: relative;
  z-index: 1;
  padding-block: clamp(38px, 6vw, 104px) clamp(44px, 6vw, 92px);
}

.page-about .about-hero .breadcrumb {
  margin: 0 0 22px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--paper-72);
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}

.page-about .about-hero .breadcrumb a {
  color: var(--paper-72);
  text-decoration: none;
  border-bottom: 1px solid rgba(246, 241, 234, .32);
  transition: color var(--t-fast), border-color var(--t-fast);
}

.page-about .about-hero .breadcrumb a:hover,
.page-about .about-hero .breadcrumb a:focus-visible {
  color: var(--gold);
  border-color: var(--gold);
}

.page-about .about-hero__kicker {
  margin: 0 0 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--gold);
}

.page-about .about-hero__title {
  margin: 0 0 22px;
  max-width: 15ch;
  font-size: clamp(40px, 7vw, 96px);
  line-height: 1.02;
  font-weight: 900;
  letter-spacing: -.02em;
}

.page-about .about-hero__lead {
  margin: 0;
  max-width: 56ch;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.85;
  color: var(--paper-80);
}

.page-about .hero-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px 24px;
  margin: clamp(34px, 5vw, 60px) 0 0;
  padding-top: 26px;
  border-top: 1px solid rgba(246, 241, 234, .18);
}

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

.page-about .hero-fact dt {
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--slate);
}

.page-about .hero-fact dd {
  margin: 0;
}

.page-about .hero-fact__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(30px, 4vw, 46px);
  line-height: 1;
  letter-spacing: -.02em;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}

.page-about .hero-fact__unit {
  display: block;
  margin-top: 8px;
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--paper-72);
}

/* ---------- 双栏骨架 ---------- */

.page-about .about-layout {
  width: min(var(--shell), 100%);
  margin-inline: auto;
  padding: clamp(30px, 4.5vw, 62px) var(--gutter) clamp(46px, 7vw, 104px);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 40px);
  align-items: start;
}

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

/* ---------- 左侧编号栏 ---------- */

.page-about .about-rail {
  border-top: 2px solid var(--flame);
  padding-top: 14px;
  min-width: 0;
}

.page-about .about-rail__title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--slate);
}

.page-about .about-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 4px;
  display: flex;
  gap: 10px;
  overflow-x: auto;
  max-width: 100%;
  scrollbar-width: thin;
}

.page-about .about-rail__list > li {
  flex: 0 0 auto;
}

.page-about .rail-link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding: 9px 12px;
  font-size: 13px;
  line-height: 1.4;
  color: var(--ink-54);
  text-decoration: none;
  border: 1px solid var(--line-light);
  border-radius: var(--radius);
  white-space: nowrap;
  transition: color var(--t-fast), border-color var(--t-fast), background var(--t-fast);
}

.page-about .rail-link:hover,
.page-about .rail-link:focus-visible {
  color: var(--flame);
  border-color: rgba(255, 77, 28, .5);
  background: rgba(255, 77, 28, .06);
}

.page-about .rail-link__num {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .06em;
  color: var(--lava);
}

/* ---------- 章节 ---------- */

.page-about .chapter {
  padding-block: clamp(30px, 4.6vw, 56px);
  border-top: 1px solid var(--line-light);
}

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

.page-about .chapter__head {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  margin-bottom: 22px;
}

.page-about .chapter__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(40px, 6vw, 72px);
  line-height: .86;
  letter-spacing: -.04em;
  color: var(--lava);
  opacity: .3;
  font-variant-numeric: tabular-nums;
}

.page-about .chapter__kicker {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--slate);
}

.page-about .chapter__title {
  margin: 0;
  font-size: clamp(24px, 3.2vw, 38px);
  line-height: 1.22;
  font-weight: 700;
  letter-spacing: -.01em;
}

.page-about .chapter p {
  max-width: 64ch;
  margin: 0 0 18px;
  font-size: 16px;
  line-height: 1.85;
  color: var(--ink-70);
}

.page-about .chapter .chapter__lead {
  font-size: clamp(17px, 1.7vw, 20px);
  line-height: 1.72;
  color: var(--ink);
}

.page-about .num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.06em;
  letter-spacing: -.01em;
  color: var(--lava);
  font-variant-numeric: tabular-nums;
}

/* 深底章节 */

.page-about .chapter--ink {
  position: relative;
  margin-block: clamp(18px, 3vw, 34px);
  padding: clamp(26px, 4vw, 52px);
  background: var(--ink);
  color: var(--paper);
  border-top-color: transparent;
}

.page-about .chapter--ink .chapter__title {
  color: var(--paper);
}

.page-about .chapter--ink .chapter__num {
  color: var(--flame);
  opacity: .42;
}

.page-about .chapter--ink p {
  color: var(--paper-72);
}

.page-about .chapter--ink .chapter .chapter__lead,
.page-about .chapter--ink .chapter__lead {
  color: var(--paper);
}

.page-about .chapter--ink .num {
  color: var(--gold);
}

/* 图文分栏 */

.page-about .split-7-5 {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3vw, 36px);
  align-items: start;
}

/* ---------- 图片 ---------- */

.page-about .about-figure {
  margin: 0;
  overflow: hidden;
  border-radius: var(--radius);
  background: linear-gradient(158deg, var(--indigo) 0%, var(--ink) 70%);
  box-shadow: var(--shadow-soft);
}

.page-about .about-figure--wide {
  margin-top: clamp(22px, 3vw, 34px);
}

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

.page-about .about-figure__caption {
  display: block;
  padding: 10px 14px 13px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--paper-72);
  background: var(--ink);
}

/* ---------- 方法四步 ---------- */

.page-about .method-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  margin-top: 26px;
}

.page-about .method-step {
  min-width: 0;
  padding: 22px 20px 26px;
  margin: -1px 0 0 -1px;
  border: 1px solid var(--line-light);
  background: rgba(255, 255, 255, .55);
  transition: background var(--t-base), border-color var(--t-base);
}

.page-about .method-step:hover,
.page-about .method-step:focus-within {
  background: #fff;
  border-color: rgba(255, 77, 28, .48);
}

.page-about .method-step__no {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--flame);
}

.page-about .method-step__title {
  margin: 0 0 10px;
  font-size: 17px;
  line-height: 1.4;
  font-weight: 700;
}

.page-about .method-step__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--ink-54);
}

/* ---------- 数据作业指标 ---------- */

.page-about .metric-list {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
}

.page-about .metric-list li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  align-items: baseline;
  gap: 4px 12px;
  padding: 18px 0;
  border-top: 1px solid var(--line-dark);
}

.page-about .metric-list__num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(24px, 3vw, 34px);
  line-height: 1;
  color: var(--gold);
  font-variant-numeric: tabular-nums;
}

.page-about .metric-list__unit {
  font-size: 13px;
  color: var(--slate);
}

.page-about .metric-list__text {
  grid-column: 1 / -1;
  margin: 8px 0 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--paper-72);
  max-width: 62ch;
}

/* ---------- 团队构成 ---------- */

.page-about .team-list {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
}

.page-about .team-row {
  padding: 17px 0;
  border-top: 1px solid var(--line-light);
}

.page-about .team-row:last-child {
  border-bottom: 1px solid var(--line-light);
}

.page-about .team-row__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 6px 16px;
}

.page-about .team-row__name {
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .team-row__count {
  font-family: var(--font-mono);
  font-size: 20px;
  letter-spacing: -.01em;
  color: var(--lava);
  font-variant-numeric: tabular-nums;
}

.page-about .chapter .team-row__desc {
  margin: 8px 0 0;
  max-width: 60ch;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--ink-54);
}

/* ---------- 时间线 ---------- */

.page-about .timeline {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 9px;
  top: 10px;
  bottom: 12px;
  width: 1px;
  background: linear-gradient(180deg, var(--gold) 0%, rgba(245, 184, 65, .18) 100%);
}

.page-about .timeline__item {
  position: relative;
  padding-left: 38px;
}

.page-about .timeline__node {
  border: 0;
}

.page-about .timeline__node > summary {
  position: relative;
  display: block;
  padding: 14px 26px 16px 0;
  cursor: pointer;
  list-style: none;
  border-bottom: 1px solid var(--line-light);
  transition: border-color var(--t-fast);
}

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

.page-about .timeline__node > summary::after {
  content: "+";
  position: absolute;
  top: 14px;
  right: 0;
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--slate);
  transition: color var(--t-fast);
}

.page-about .timeline__node[open] > summary::after {
  content: "–";
  color: var(--flame);
}

.page-about .timeline__node[open] > summary {
  border-bottom-color: rgba(255, 77, 28, .45);
}

.page-about .timeline__dot {
  position: absolute;
  left: -34px;
  top: 20px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--gold);
  box-shadow: 0 0 0 4px rgba(245, 184, 65, .18);
}

.page-about .timeline__season {
  display: block;
  margin-bottom: 4px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--lava);
}

.page-about .timeline__title {
  display: block;
  font-size: 17px;
  line-height: 1.45;
  font-weight: 700;
  color: var(--ink);
}

.page-about .timeline__body {
  padding: 4px 0 18px;
}

.page-about .chapter .timeline__body p {
  margin: 0;
  max-width: 60ch;
  font-size: 15px;
  line-height: 1.82;
  color: var(--ink-70);
}

/* ---------- 合作生态 ---------- */

.page-about .partner-list {
  list-style: none;
  margin: 26px 0 4px;
  padding: 0;
}

.page-about .partner {
  padding: 20px 0;
  border-top: 1px solid var(--line-light);
}

.page-about .partner:last-child {
  border-bottom: 1px solid var(--line-light);
}

.page-about .partner__title {
  margin: 0 0 10px;
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.35;
  font-weight: 700;
  color: var(--ink);
}

.page-about .chapter .partner__text {
  margin: 0;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-70);
}

/* ---------- 文末入口 ---------- */

.page-about .about-cta {
  position: relative;
  overflow: hidden;
  margin-top: clamp(28px, 4vw, 46px);
  padding: clamp(28px, 4vw, 52px);
  background: linear-gradient(140deg, var(--indigo) 0%, #131f33 100%);
  color: var(--paper);
}

.page-about .about-cta::before {
  content: "";
  position: absolute;
  top: -30%;
  right: -14%;
  width: 56%;
  height: 170%;
  background: linear-gradient(140deg, rgba(255, 77, 28, .88) 0%, rgba(179, 33, 14, .38) 58%, rgba(27, 42, 68, 0) 100%);
  transform: skewX(-15deg);
  pointer-events: none;
}

.page-about .about-cta__title {
  position: relative;
  margin: 0 0 12px;
  font-size: clamp(22px, 2.8vw, 32px);
  line-height: 1.26;
  font-weight: 700;
}

.page-about .about-cta__lead {
  position: relative;
  margin: 0 0 24px;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.82;
  color: var(--paper-80);
}

.page-about .about-cta__links {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .cta-link {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 12px 18px;
  font-size: 14px;
  color: var(--paper);
  text-decoration: none;
  border: 1px solid rgba(246, 241, 234, .32);
  border-radius: var(--radius);
  transition: background var(--t-fast), border-color var(--t-fast), color var(--t-fast);
}

.page-about .cta-link::after {
  content: "→";
  font-family: var(--font-mono);
  font-size: 14px;
}

.page-about .cta-link:hover,
.page-about .cta-link:focus-visible {
  background: var(--flame);
  border-color: var(--flame);
  color: #fff;
}

/* ---------- 断点 ---------- */

@media (min-width: 560px) {
  .page-about .chapter__head {
    grid-template-columns: auto minmax(0, 1fr);
    gap: 12px 18px;
    align-items: start;
  }
}

@media (min-width: 720px) {
  .page-about .hero-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

  .page-about .metric-list li {
    grid-template-columns: auto auto minmax(0, 1fr);
    gap: 6px 14px;
  }

  .page-about .metric-list__text {
    grid-column: auto;
    margin-top: 0;
  }
}

@media (min-width: 860px) {
  .page-about .split-7-5 {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  }
}

@media (min-width: 1024px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(36px, 5vw, 80px);
  }

  .page-about .about-rail {
    position: sticky;
    top: 104px;
  }

  .page-about .about-rail__list {
    display: block;
    overflow: visible;
    padding-bottom: 0;
  }

  .page-about .about-rail__list > li {
    flex: none;
  }

  .page-about .rail-link {
    display: grid;
    grid-template-columns: 28px minmax(0, 1fr);
    gap: 10px;
    padding: 11px 0;
    font-size: 13.5px;
    line-height: 1.5;
    white-space: normal;
    border: 0;
    border-top: 1px solid var(--line-light);
    border-radius: 0;
    background: none;
  }

  .page-about .rail-link:hover,
  .page-about .rail-link:focus-visible {
    color: var(--flame);
    background: none;
  }
}

@media (min-width: 1100px) {
  .page-about .method-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .method-step,
  .page-about .rail-link,
  .page-about .cta-link,
  .page-about .timeline__node > summary::after {
    transition: none;
  }
}