.page-about {
  --about-sticky: 96px;
  background: var(--ink-900);
  color: var(--paper);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  padding: clamp(22px, 4vw, 44px) 0 clamp(44px, 7vw, 96px);
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--cyan) 0%, rgba(56, 225, 207, 0.08) 52%, rgba(56, 225, 207, 0) 100%);
  opacity: 0.55;
}

.page-about .about-hero__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 4vw, 40px);
  align-items: end;
}

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

.page-about .about-hero__title {
  margin: 16px 0 0;
  font-family: var(--font-display);
  font-weight: 250;
  font-size: clamp(2.4rem, 9.5vw, 5.6rem);
  line-height: 0.98;
  letter-spacing: -0.015em;
  color: var(--paper);
}

.page-about .about-hero__aside {
  min-width: 0;
  display: grid;
  gap: clamp(12px, 2vw, 18px);
}

.page-about .about-hero__lede {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--paper);
}

.page-about .about-hero__facts {
  margin: 4px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 10px;
  font-family: var(--font-data);
  font-variant-numeric: tabular-nums;
  font-size: 0.875rem;
  letter-spacing: 0.04em;
  color: var(--muted);
}

.page-about .about-hero__facts .data-num {
  color: var(--cyan);
  font-size: 1.0625rem;
  font-weight: 500;
}

.page-about .about-hero__dot {
  color: rgba(147, 170, 163, 0.45);
}

@media (min-width: 920px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr);
    gap: clamp(32px, 5vw, 76px);
  }
}

/* ---------- 章节头 ---------- */

.page-about .about-track {
  padding: clamp(44px, 7vw, 88px) 0 clamp(48px, 8vw, 104px);
}

.page-about .about-track__head {
  margin-bottom: clamp(26px, 4vw, 48px);
}

/* ---------- 时间轴 ---------- */

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

.page-about .timeline__item {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(12px, 2vw, 18px);
  padding: clamp(34px, 5vw, 62px) 0;
  border-top: 1px solid var(--line);
}

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

.page-about .timeline__aside {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  min-width: 0;
}

.page-about .timeline__year {
  display: inline-block;
  padding: 0;
  margin: 0;
  background: none;
  border: 0;
  font-family: var(--font-data);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.9rem, 9vw, 4.2rem);
  font-weight: 300;
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--cyan);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}

.page-about .timeline__year:hover,
.page-about .timeline__year:focus-visible {
  color: var(--amber);
}

.page-about .timeline__tag {
  align-self: center;
}

.page-about .timeline__main {
  min-width: 0;
  max-width: 68ch;
}

.page-about .timeline__title {
  margin: 0 0 0.75em;
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: clamp(1.4rem, 3.6vw, 2.1rem);
  line-height: 1.28;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .timeline__title::before {
  content: "";
  display: block;
  width: 30px;
  height: 2px;
  margin-bottom: 0.7em;
  background: var(--cyan);
}

.page-about .timeline__main p {
  margin: 0 0 1.05em;
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--paper);
}

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

@media (min-width: 900px) {
  .page-about .timeline__item {
    grid-template-columns: minmax(0, 1fr) minmax(0, 2.2fr);
    gap: clamp(28px, 4vw, 64px);
    padding: clamp(40px, 5vw, 72px) 0;
  }

  .page-about .timeline__aside {
    display: block;
    position: sticky;
    top: var(--about-sticky);
    padding-right: clamp(16px, 2.4vw, 32px);
    border-right: 1px solid rgba(56, 225, 207, 0.16);
  }

  .page-about .timeline__tag {
    display: inline-block;
    margin-top: 16px;
  }
}

/* ---------- 图片 ---------- */

.page-about .timeline__media {
  margin: clamp(22px, 3.5vw, 36px) 0 0;
}

.page-about .timeline__media img,
.page-about .about-collab__figure img {
  width: 100%;
  height: auto;
  display: block;
  filter: saturate(0.82) contrast(1.05) brightness(0.94);
}

/* ---------- 四条主线 ---------- */

.page-about .about-lines {
  list-style: none;
  margin: 10px 0 0;
  padding: 0;
  counter-reset: aboutline;
}

.page-about .about-lines__item {
  position: relative;
  counter-increment: aboutline;
  padding: 18px 0 18px 52px;
  border-top: 1px solid var(--line);
}

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

.page-about .about-lines__item::before {
  content: counter(aboutline, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 21px;
  font-family: var(--font-data);
  font-variant-numeric: tabular-nums;
  font-size: 0.8125rem;
  letter-spacing: 0.1em;
  color: var(--amber);
}

.page-about .about-lines__key {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1.125rem;
  letter-spacing: 0.02em;
  color: var(--paper);
}

.page-about .about-lines__desc {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--muted);
}

/* ---------- 团队分工 ---------- */

.page-about .about-team {
  margin: 10px 0 0;
  border-top: 1px solid var(--line);
}

.page-about .about-team__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 6px;
  padding: 15px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .about-team__name {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.06em;
  color: var(--amber);
}

.page-about .about-team__desc {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--paper);
}

.page-about .about-team__foot {
  margin: 18px 0 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--muted);
}

@media (min-width: 640px) {
  .page-about .about-team__row {
    grid-template-columns: 108px minmax(0, 1fr);
    gap: 22px;
    align-items: baseline;
  }
}

/* ---------- 覆盖范围 ---------- */

.page-about .about-scope {
  margin: 22px 0;
  padding: clamp(18px, 3vw, 28px);
  background: var(--ink-800);
  border: 1px solid var(--line);
  box-shadow: 6px 6px 0 rgba(5, 14, 12, 0.85), 12px 12px 0 rgba(30, 58, 49, 0.32);
}

.page-about .about-scope__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .about-scope__list li {
  padding: 6px 12px;
  border: 1px solid var(--line);
  background: var(--ink-900);
  font-family: var(--font-heading);
  font-size: 0.9375rem;
  letter-spacing: 0.06em;
  color: var(--paper);
}

.page-about .about-scope__list li.about-scope__more {
  color: var(--cyan);
  border-color: rgba(56, 225, 207, 0.42);
  background: transparent;
}

/* ---------- 里程碑折叠 ---------- */

.page-about .about-miles {
  margin: 12px 0 0;
  border-top: 1px solid var(--line);
}

.page-about .about-mile {
  border-bottom: 1px solid var(--line);
}

.page-about .about-mile__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) 16px;
  align-items: center;
  gap: 14px;
  padding: 16px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-mile__head:hover .about-mile__name,
.page-about .about-mile__head:focus-visible .about-mile__name {
  color: var(--cyan);
}

.page-about .about-mile__year {
  font-family: var(--font-data);
  font-variant-numeric: tabular-nums;
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  color: var(--amber);
  white-space: nowrap;
}

.page-about .about-mile__name {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1.0625rem;
  line-height: 1.5;
  color: var(--paper);
  transition: color var(--dur) var(--ease);
}

.page-about .about-mile__chev {
  position: relative;
  display: block;
  width: 16px;
  height: 16px;
}

.page-about .about-mile__chev::before,
.page-about .about-mile__chev::after {
  content: "";
  position: absolute;
  background: var(--cyan);
  transition: transform var(--dur) var(--ease), opacity var(--dur) var(--ease);
}

.page-about .about-mile__chev::before {
  left: 0;
  right: 0;
  top: 7px;
  height: 1px;
}

.page-about .about-mile__chev::after {
  top: 0;
  bottom: 0;
  left: 7px;
  width: 1px;
}

.page-about .about-mile[open] .about-mile__chev::after {
  transform: scaleY(0);
  opacity: 0;
}

.page-about .about-mile__body {
  padding: 0 0 20px;
}

.page-about .about-mile__body p {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--muted);
}

@media (min-width: 640px) {
  .page-about .about-mile__head {
    grid-template-columns: 6.5em minmax(0, 1fr) 16px;
  }
}

/* ---------- 接下来 ---------- */

.page-about .about-next {
  list-style: none;
  margin: 10px 0 0;
  padding: 0;
}

.page-about .about-next__item {
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

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

.page-about .about-next__tag {
  display: inline-block;
  margin-bottom: 10px;
}

.page-about .about-next__item p {
  margin: 0;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--paper);
}

/* ---------- 结尾入口 ---------- */

.page-about .about-cta {
  margin-top: clamp(40px, 6vw, 72px);
  padding: clamp(24px, 4vw, 42px);
  background: var(--ink-800);
  border: 1px solid var(--line);
  box-shadow: 8px 8px 0 rgba(5, 14, 12, 0.88), 16px 16px 0 rgba(30, 58, 49, 0.3);
}

.page-about .about-cta__text {
  margin: 0 0 22px;
  max-width: 62ch;
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--paper);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .about-cta__help {
  margin: 26px 0 0;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  font-family: var(--font-body);
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .about-cta__help a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(56, 225, 207, 0.42);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-cta__help a:hover,
.page-about .about-cta__help a:focus-visible {
  color: var(--amber);
  border-bottom-color: rgba(255, 182, 60, 0.6);
}

/* ---------- 窄屏收尾 ---------- */

@media (max-width: 420px) {
  .page-about .about-hero__title {
    font-size: 2.15rem;
  }

  .page-about .about-lines__item {
    padding-left: 42px;
  }

  .page-about .about-scope {
    box-shadow: 4px 4px 0 rgba(5, 14, 12, 0.85);
  }

  .page-about .about-cta {
    box-shadow: 5px 5px 0 rgba(5, 14, 12, 0.85);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .timeline__year,
  .page-about .about-mile__name,
  .page-about .about-mile__chev::before,
  .page-about .about-mile__chev::after,
  .page-about .about-cta__help a {
    transition: none;
  }
}