.page-about {
  --about-text: #2b333b;
  --about-accent: var(--coral);
  --about-accent-deep: var(--coral-700);
  --about-rule: rgba(28, 90, 128, 0.22);
  display: block;
  background: var(--mist);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* ---------- 首屏 ---------- */

.page-about .about-masthead {
  position: relative;
  overflow: hidden;
  padding: 20px 0 56px;
  background: var(--sea-900);
  border-bottom: 1px solid rgba(242, 169, 59, 0.5);
  color: var(--pearl);
}

.page-about .about-masthead::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--grid-line-deep) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line-deep) 1px, transparent 1px);
  background-size: 44px 44px;
  pointer-events: none;
}

.page-about .about-masthead::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  width: 26%;
  height: 4px;
  background: var(--coral);
}

.page-about .about-masthead .shell {
  position: relative;
  z-index: 1;
}

.page-about .breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  line-height: 1.6;
}

.page-about .breadcrumbs__item {
  color: var(--gold);
}

.page-about .breadcrumbs__link {
  color: rgba(232, 238, 242, 0.7);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 160ms ease, border-color 160ms ease;
}

.page-about .breadcrumbs__link:hover,
.page-about .breadcrumbs__link:focus-visible {
  color: var(--coral);
  border-bottom-color: var(--coral);
}

.page-about .breadcrumbs__sep {
  color: rgba(232, 238, 242, 0.38);
}

.page-about .about-masthead__eyebrow {
  margin: 30px 0 16px;
  color: var(--gold);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.page-about .about-masthead__title {
  margin: 0;
  max-width: 17em;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(29px, 7vw, 56px);
  line-height: 1.16;
  letter-spacing: -0.01em;
}

.page-about .about-masthead__lead {
  margin: 22px 0 0;
  max-width: 40em;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(232, 238, 242, 0.82);
}

.page-about .about-masthead__facts {
  list-style: none;
  margin: 38px 0 0;
  padding: 22px 0 0;
  border-top: 1px solid var(--line-light);
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

.page-about .about-masthead__facts li {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 14px;
  color: rgba(232, 238, 242, 0.66);
}

.page-about .about-masthead__facts .mono {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 15px;
  letter-spacing: 0.02em;
  color: var(--coral);
}

@media (min-width: 720px) {
  .page-about .about-masthead__facts {
    grid-template-columns: repeat(3, auto);
    justify-content: start;
    gap: 56px;
  }
}

/* ---------- 主体骨架 ---------- */

.page-about .about-body {
  padding: 48px 0 104px;
}

.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 36px;
}

@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: 220px minmax(0, 1fr);
    gap: 76px;
    align-items: start;
  }

  .page-about .toc-wrap {
    position: sticky;
    top: 32px;
  }
}

/* ---------- 目录 ---------- */

.page-about .toc {
  border-top: 1px solid var(--line-soft);
  padding-top: 16px;
}

@media (min-width: 1000px) {
  .page-about .toc {
    border-top: 0;
    border-left: 1px solid var(--line-soft);
    padding: 4px 0 4px 18px;
  }
}

.page-about .toc__title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--slate);
}

.page-about .toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px 18px;
}

@media (min-width: 1000px) {
  .page-about .toc__list {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
  }
}

.page-about .toc__link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 7px 0;
  color: var(--sea-700);
  font-size: 14px;
  text-decoration: none;
  transition: color 160ms ease;
}

.page-about .toc__num {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  color: var(--slate);
  transition: color 160ms ease;
}

.page-about .toc__link:hover,
.page-about .toc__link:focus-visible {
  color: var(--about-accent-deep);
}

.page-about .toc__link:hover .toc__num,
.page-about .toc__link:focus-visible .toc__num {
  color: var(--about-accent);
}

.page-about .toc__link.is-active {
  color: var(--about-accent-deep);
}

.page-about .toc__link.is-active .toc__num {
  color: var(--about-accent);
}

/* ---------- 章节 ---------- */

.page-about .about-section {
  padding: 44px 0 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-section + .about-section {
  margin-top: 56px;
}

.page-about .about-section__head {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 6px;
  margin-bottom: 26px;
}

@media (min-width: 720px) {
  .page-about .about-section__head {
    grid-template-columns: 76px minmax(0, 1fr);
    gap: 26px;
    align-items: start;
  }
}

.page-about .section-index {
  display: block;
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 30px;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--sea-500);
}

@media (min-width: 720px) {
  .page-about .section-index {
    font-size: 40px;
    padding-top: 2px;
  }
}

.page-about .section-title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(21px, 3.6vw, 30px);
  line-height: 1.34;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .section-lead {
  margin: 12px 0 0;
  max-width: 32em;
  font-family: var(--font-serif);
  font-size: 16.5px;
  line-height: 1.7;
  color: var(--sea-700);
}

.page-about .about-section__body p {
  max-width: 34em;
  margin: 0 0 20px;
  font-size: 16px;
  line-height: 1.78;
  color: var(--about-text);
}

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

.page-about .about-section__prose p {
  max-width: 34em;
  margin: 0 0 18px;
  font-size: 16px;
  line-height: 1.78;
  color: var(--about-text);
}

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

.page-about .about-section__split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
}

@media (min-width: 860px) {
  .page-about .about-section__split {
    grid-template-columns: minmax(0, 1.04fr) minmax(0, 0.96fr);
    gap: 44px;
    align-items: start;
  }
}

/* ---------- 图片容器 ---------- */

.page-about .media-frame {
  margin: 0;
  background: var(--sea-900);
  border: 1px solid var(--line);
  overflow: hidden;
}

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

.page-about .media-frame__caption {
  display: block;
  padding: 12px 14px;
  background: var(--pearl);
  border-top: 1px solid var(--line-soft);
  font-size: 13px;
  line-height: 1.7;
  color: var(--slate);
}

/* ---------- 六条原则 ---------- */

.page-about .about-principles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

@media (min-width: 640px) {
  .page-about .about-principles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1080px) {
  .page-about .about-principles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .about-principles > li {
  position: relative;
  padding: 24px 22px 26px;
  background: var(--pearl);
  border-top: 3px solid transparent;
  transition: border-color 200ms ease, background 200ms ease;
}

.page-about .about-principles > li:hover {
  border-top-color: var(--about-accent);
  background: #ffffff;
}

.page-about .about-principles__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--about-accent-deep);
}

.page-about .about-principles__title {
  margin: 8px 0 10px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 19px;
  letter-spacing: -0.005em;
  color: var(--ink);
}

.page-about .about-principles__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.74;
  color: var(--about-text);
}

/* ---------- 时间轴 ---------- */

.page-about .about-timeline {
  margin-top: 4px;
  padding-bottom: 10px;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scrollbar-color: var(--sea-500) transparent;
}

.page-about .about-timeline__track {
  display: flex;
  min-width: max-content;
  padding-top: 26px;
}

.page-about .about-timeline__node {
  position: relative;
  flex: 0 0 auto;
  width: 220px;
  padding: 0 22px 0 0;
  border-right: 1px solid var(--line-soft);
}

.page-about .about-timeline__node:last-child {
  border-right: 0;
  padding-right: 0;
}

.page-about .about-timeline__node::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: var(--line-soft);
}

.page-about .about-timeline__node:last-child::before {
  right: 22px;
}

.page-about .about-timeline__marker {
  position: absolute;
  top: -4px;
  left: 0;
  width: 9px;
  height: 9px;
  background: var(--gold);
}

.page-about .about-timeline__node--active .about-timeline__marker {
  background: var(--about-accent);
  box-shadow: 0 0 0 4px rgba(255, 107, 61, 0.18);
}

.page-about .about-timeline__version {
  display: block;
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 19px;
  line-height: 1.25;
  letter-spacing: -0.01em;
  color: var(--sea-900);
}

.page-about .about-timeline__node--active .about-timeline__version {
  color: var(--about-accent-deep);
}

.page-about .about-timeline__label {
  display: block;
  margin-top: 6px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--slate);
}

.page-about .about-timeline__note {
  display: block;
  margin-top: 0;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  font-size: 13.5px;
  line-height: 1.68;
  color: var(--sea-700);
  transition: max-height 220ms ease, opacity 220ms ease, margin-top 220ms ease;
}

.page-about .about-timeline__node:hover .about-timeline__note,
.page-about .about-timeline__node:focus-within .about-timeline__note {
  max-height: 140px;
  margin-top: 10px;
  opacity: 1;
}

@media (hover: none) {
  .page-about .about-timeline__note {
    max-height: 140px;
    margin-top: 10px;
    opacity: 1;
  }
}

/* ---------- 团队 ---------- */

.page-about .about-team {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 30px;
}

@media (min-width: 900px) {
  .page-about .about-team {
    grid-template-columns: minmax(0, 0.92fr) minmax(0, 1.08fr);
    gap: 44px;
    align-items: start;
  }
}

.page-about .about-team__overview {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  border-top: 1px solid var(--line);
  border-left: 1px solid var(--line);
}

.page-about .about-team__overview .overview__item {
  padding: 20px 18px 22px;
  background: var(--pearl);
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  transition: background 180ms ease;
}

.page-about .about-team__overview .overview__item:hover,
.page-about .about-team__overview .overview__item:focus-within {
  background: #ffffff;
}

.page-about .about-team__overview .overview__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 36px;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--sea-900);
}

.page-about .about-team__overview .overview__label {
  display: block;
  margin-top: 10px;
  font-size: 14px;
  color: var(--slate);
}

.page-about .about-hint {
  display: block;
  max-height: 0;
  margin-top: 0;
  overflow: hidden;
  opacity: 0;
  font-size: 13px;
  line-height: 1.66;
  color: var(--sea-700);
  transition: max-height 200ms ease, opacity 200ms ease, margin-top 200ms ease;
}

.page-about .about-team__overview .overview__item:hover .about-hint,
.page-about .about-team__overview .overview__item:focus-within .about-hint {
  max-height: 100px;
  margin-top: 10px;
  opacity: 1;
}

@media (hover: none) {
  .page-about .about-hint {
    max-height: 100px;
    margin-top: 10px;
    opacity: 1;
  }
}

.page-about .about-team__reach {
  margin: 24px 0 0;
  padding-left: 16px;
  border-left: 3px solid var(--about-accent);
  font-size: 15px;
  line-height: 1.8;
  color: var(--about-text);
}

.page-about .stat-num {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 1.06em;
  color: var(--about-accent-deep);
}

/* ---------- 分类体系 ---------- */

.page-about .about-taxonomy__figure {
  margin-top: 30px;
}

.page-about .about-taxonomy__tiers {
  list-style: none;
  margin: 30px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

@media (min-width: 760px) {
  .page-about .about-taxonomy__tiers {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .about-taxonomy__tiers > li {
  padding: 24px 22px 26px;
  background: var(--sea-900);
}

.page-about .about-taxonomy__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 32px;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--coral);
}

.page-about .about-taxonomy__title {
  margin: 12px 0 8px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 17px;
  color: var(--pearl);
}

.page-about .about-taxonomy__tiers p {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: rgba(232, 238, 242, 0.72);
}

/* ---------- 合作与入口 ---------- */

.page-about .about-next {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

/* ---------- 动效 ---------- */

.page-about .reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 340ms ease-out, transform 340ms ease-out;
}

.page-about .reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

@media (prefers-reduced-motion: reduce) {
  .page-about .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .page-about .about-timeline__note,
  .page-about .about-hint {
    transition: none;
  }
}

@media (max-width: 480px) {
  .page-about .about-masthead__title {
    font-size: 27px;
  }

  .page-about .section-index {
    font-size: 26px;
  }

  .page-about .about-team__overview .overview__num {
    font-size: 30px;
  }

  .page-about .about-timeline__node {
    width: 190px;
  }
}