.page-about {
  background: var(--mist-050);
  color: var(--ink-900);
  font-family: var(--font-body);
}

.page-about .section {
  padding: var(--s-8) 0;
  border-top: var(--line);
}

.page-about .about-hero {
  border-top: 0;
  padding-top: var(--s-6);
}

/* ---------- 顶部条 ---------- */
.page-about .about-topbar {
  background: var(--paper);
  border-bottom: var(--line);
}

.page-about .about-topbar__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--s-1) var(--s-3);
  min-height: 52px;
  padding-top: var(--s-1);
  padding-bottom: var(--s-1);
}

.page-about .about-topbar .breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--fog-600);
}

.page-about .about-topbar .breadcrumbs__link {
  color: var(--lake-700);
  text-decoration: none;
}

.page-about .about-topbar .breadcrumbs__link:hover {
  color: var(--orange-500);
}

.page-about .about-topbar .breadcrumbs__item {
  color: var(--fog-600);
}

.page-about .about-topbar__sep {
  margin: 0 var(--s-1);
  color: var(--mist-200);
}

.page-about .about-topbar__status {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--fog-600);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero__grid {
  display: grid;
  gap: var(--s-6);
  align-items: center;
}

.page-about .about-hero__title {
  margin: var(--s-2) 0 var(--s-3);
  font-family: var(--font-heading);
  font-weight: 900;
  font-size: clamp(2rem, 5.4vw, 3.5rem);
  line-height: 1.06;
  letter-spacing: -0.02em;
  color: var(--ink-900);
  max-width: 15ch;
}

.page-about .about-hero__lead {
  margin: 0;
  max-width: 44ch;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--fog-600);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--s-2);
  margin-top: var(--s-4);
}

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

.page-about .figure__frame {
  overflow: hidden;
  background: var(--lake-900);
}

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

.page-about .about-hero__figure .figure__frame {
  aspect-ratio: 16 / 9;
}

.page-about .figure__caption {
  margin-top: var(--s-1);
  font-size: 12px;
  line-height: 1.6;
  letter-spacing: 0.04em;
  color: var(--fog-600);
}

/* ---------- 规模数字 ---------- */
.page-about .about-scale__intro {
  max-width: 64ch;
  margin: 0 0 var(--s-6);
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--ink-900);
}

.page-about .about-scale__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--s-4) var(--s-3);
}

.page-about .about-scale__item {
  border-top: var(--line);
  padding-top: var(--s-2);
}

.page-about .about-scale__num {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.9rem, 4vw, 2.6rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--orange-500);
}

.page-about .about-scale__key {
  display: block;
  margin-top: var(--s-1);
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--lake-700);
  letter-spacing: 0.02em;
}

.page-about .about-scale__txt {
  margin: var(--s-1) 0 0;
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--fog-600);
}

/* ---------- 时间轴 ---------- */
.page-about .about-timeline__intro {
  max-width: 54ch;
  margin: 0 0 var(--s-6);
  line-height: 1.85;
  color: var(--fog-600);
}

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

.page-about .about-timeline__list::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  background: var(--lake-100);
}

.page-about .about-timeline__item {
  position: relative;
  padding-left: 36px;
  padding-bottom: var(--s-4);
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 5px;
  width: 14px;
  height: 14px;
  box-sizing: border-box;
  background: var(--paper);
  border: 2px solid var(--lake-500);
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-timeline__item:has(.about-timeline__node[open])::before {
  background: var(--orange-500);
  border-color: var(--orange-500);
}

.page-about .about-timeline__summary {
  position: relative;
  display: block;
  padding-right: var(--s-4);
  cursor: pointer;
  list-style: none;
}

.page-about .about-timeline__summary::-webkit-details-marker {
  display: none;
}

.page-about .about-timeline__summary::after {
  content: "+";
  position: absolute;
  right: 0;
  top: 0;
  font-family: var(--font-mono);
  font-size: 1.125rem;
  line-height: 1.3;
  color: var(--fog-600);
  transition: color var(--dur) var(--ease);
}

.page-about .about-timeline__node[open] .about-timeline__summary::after {
  content: "–";
  color: var(--orange-500);
}

.page-about .about-timeline__stage {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--orange-500);
}

.page-about .about-timeline__name {
  display: block;
  margin-top: 2px;
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink-900);
}

.page-about .about-timeline__body {
  padding-top: var(--s-1);
}

.page-about .about-timeline__body p {
  margin: 0;
  max-width: 60ch;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--fog-600);
}

/* ---------- 数据流程 ---------- */
.page-about .about-flow__split {
  align-items: start;
}

.page-about .about-flow__lead {
  margin: 0 0 var(--s-4);
  max-width: 48ch;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--ink-900);
}

.page-about .about-flow__list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-flow__step {
  position: relative;
  padding: var(--s-3) 0 var(--s-3) var(--s-6);
  border-top: var(--line);
}

.page-about .about-flow__step:last-child {
  border-bottom: var(--line);
}

.page-about .about-flow__idx {
  position: absolute;
  left: 0;
  top: var(--s-3);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--orange-500);
}

.page-about .about-flow__title {
  margin: 0 0 var(--s-1);
  font-size: 1.0625rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink-900);
}

.page-about .about-flow__step p {
  margin: 0;
  max-width: 46ch;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--fog-600);
}

.page-about .about-flow__note {
  margin: var(--s-4) 0 0;
  padding-left: var(--s-2);
  border-left: 3px solid var(--orange-500);
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--lake-900);
}

.page-about .about-flow__figure .figure__frame {
  aspect-ratio: 4 / 3;
}

.page-about .about-flow__figure {
  margin-top: var(--s-6);
}

/* ---------- 团队 ---------- */
.page-about .about-team__grid {
  display: grid;
  gap: var(--s-6);
}

.page-about .about-team__intro p {
  margin: 0 0 var(--s-3);
  max-width: 40ch;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--ink-900);
}

.page-about .about-team__link {
  color: var(--lake-700);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-team__link:hover {
  color: var(--orange-500);
}

.page-about .about-team__roles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--s-3);
}

.page-about .about-team__role {
  background: var(--paper);
  border: var(--line);
  border-left: 3px solid var(--lake-700);
  padding: var(--s-3);
}

.page-about .about-team__role-idx {
  display: block;
  margin-bottom: var(--s-1);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--fog-600);
}

.page-about .about-team__role h3 {
  margin: 0 0 var(--s-1);
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--ink-900);
}

.page-about .about-team__role p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--fog-600);
}

/* ---------- 用户构成 ---------- */
.page-about .about-audience__split {
  align-items: start;
}

.page-about .about-audience__figure .figure__frame {
  aspect-ratio: 1 / 1;
}

.page-about .about-audience__bar {
  list-style: none;
  margin: 0 0 var(--s-4);
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px;
}

.page-about .about-audience__seg {
  padding: var(--s-2);
  font-size: 0.8125rem;
  font-weight: 700;
  line-height: 1.45;
  letter-spacing: 0.02em;
  color: var(--paper);
  background: var(--lake-700);
  transition: background var(--dur) var(--ease);
}

.page-about .about-audience__seg--media {
  background: var(--lake-500);
}

.page-about .about-audience__seg--union {
  background: var(--orange-500);
}

.page-about .about-audience__seg--campus {
  background: var(--lake-900);
}

.page-about .about-audience__seg:hover {
  background: var(--lake-100);
  color: var(--ink-900);
}

.page-about .about-audience__cards {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--s-2);
}

.page-about .about-audience__card {
  border-top: var(--line);
  padding-top: var(--s-2);
}

.page-about .about-audience__card h3 {
  margin: 0 0 var(--s-1);
  font-size: 1rem;
  font-weight: 700;
  color: var(--ink-900);
}

.page-about .about-audience__card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--fog-600);
}

.page-about .about-audience__note {
  margin: var(--s-4) 0 0;
  padding: var(--s-2) var(--s-3);
  background: var(--lake-100);
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--lake-900);
}

/* ---------- 白皮书 ---------- */
.page-about .about-whitepaper__grid {
  display: grid;
  gap: var(--s-5, 40px);
}

.page-about .about-whitepaper__lead {
  margin: 0;
  max-width: 46ch;
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--ink-900);
}

.page-about .about-whitepaper__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--s-3);
}

.page-about .about-whitepaper__item {
  padding-left: var(--s-3);
  border-left: 1px solid var(--mist-200);
}

.page-about .about-whitepaper__item h3 {
  margin: 0 0 var(--s-1);
  font-size: 1rem;
  font-weight: 700;
  color: var(--lake-700);
  letter-spacing: 0.01em;
}

.page-about .about-whitepaper__item p {
  margin: 0;
  max-width: 52ch;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--fog-600);
}

.page-about .about-whitepaper__link {
  color: var(--lake-700);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-whitepaper__link:hover {
  color: var(--orange-500);
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  background: var(--paper);
}

.page-about .about-next__grid {
  display: grid;
  gap: var(--s-4);
}

.page-about .about-next__title {
  margin: var(--s-1) 0 0;
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--ink-900);
  max-width: 14ch;
}

.page-about .about-next__links {
  display: grid;
  gap: var(--s-2);
}

.page-about .about-next__link {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  column-gap: var(--s-2);
  align-items: baseline;
  padding: var(--s-3);
  background: var(--mist-050);
  border: var(--line);
  text-decoration: none;
  transition: border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.page-about .about-next__link-idx {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--fog-600);
  transition: color var(--dur) var(--ease);
}

.page-about .about-next__link-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--lake-700);
}

.page-about .about-next__link-desc {
  grid-column: 2;
  margin-top: var(--s-1);
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--fog-600);
}

.page-about .about-next__link:hover {
  background: var(--paper);
  border-color: var(--lake-500);
}

.page-about .about-next__link:hover .about-next__link-idx {
  color: var(--orange-500);
}

/* ---------- 响应式 ---------- */
@media (min-width: 620px) {
  .page-about .about-team__roles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-audience__bar {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 720px) {
  .page-about .about-scale__list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .about-timeline__stage {
    display: inline-block;
    min-width: 10em;
  }

  .page-about .about-timeline__name {
    display: inline;
    margin-top: 0;
  }

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

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

  .page-about .about-next__link-desc {
    grid-column: 1;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--s-8);
  }

  .page-about .about-team__grid {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
    gap: var(--s-8);
  }

  .page-about .about-whitepaper__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    gap: var(--s-8);
  }

  .page-about .about-next__grid {
    grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
    gap: var(--s-8);
    align-items: start;
  }

  .page-about .about-timeline__item {
    padding-left: 52px;
  }
}

@media (min-width: 1100px) {
  .page-about .about-scale__list {
    grid-template-columns: repeat(6, minmax(0, 1fr));
    gap: var(--s-3);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-timeline__summary::after,
  .page-about .about-timeline__item::before,
  .page-about .about-audience__seg,
  .page-about .about-next__link,
  .page-about .about-next__link-idx {
    transition: none;
  }
}

.page-about {
  --s-5: 1rem;
}