.page-about {
  --about-rail-w: 96px;
  --about-ink-dark: #061420;
  background: var(--bg-page);
  color: var(--ink);
  font-family: var(--font-sans);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  background: var(--c-polar);
  color: var(--c-ice);
  padding: clamp(20px, 3.5vw, 34px) 0 clamp(52px, 8vw, 104px);
}

.page-about .about-hero__shard {
  position: absolute;
  right: -22%;
  top: 14%;
  width: 66%;
  height: 96%;
  background: linear-gradient(148deg, var(--c-glacier) 0%, var(--c-moss) 100%);
  transform: rotate(-9deg);
  border-radius: var(--r-lg);
  opacity: .55;
  pointer-events: none;
}

.page-about .about-hero .wrap {
  position: relative;
  z-index: 1;
}

.page-about .about-hero .breadcrumb__list {
  color: var(--c-tundra);
  font-size: 13px;
}

.page-about .about-hero .breadcrumb a {
  color: var(--c-frost);
  text-decoration: none;
}

.page-about .about-hero .breadcrumb a:hover {
  color: var(--c-lava);
}

.page-about .about-hero .eyebrow {
  margin: clamp(26px, 5vw, 52px) 0 14px;
  color: var(--c-neon);
}

.page-about .about-hero__title {
  margin: 0;
  max-width: 18em;
  font-size: clamp(36px, 6.6vw, 88px);
  font-weight: 800;
  line-height: 1.04;
  letter-spacing: -.035em;
  color: var(--c-ice);
}

.page-about .about-hero__lead {
  margin: clamp(20px, 3vw, 30px) 0 0;
  max-width: 34em;
  font-size: clamp(15px, 1.5vw, 18px);
  line-height: 1.8;
  color: var(--c-frost);
}

.page-about .about-hero__meta {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px 22px;
  margin-top: clamp(34px, 5vw, 58px);
  padding-top: 26px;
  border-top: 1px solid var(--line-dark);
}

.page-about .about-hero__meta .stat__value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(22px, 3vw, 36px);
  font-weight: 700;
  letter-spacing: -.02em;
  color: var(--c-ice);
}

.page-about .about-hero__meta .stat__label {
  display: block;
  margin-top: 7px;
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--c-tundra);
}

/* ---------- 章节索引轨道 ---------- */
.page-about .about-index {
  background: var(--c-glacier);
  color: var(--c-ice);
  padding: clamp(20px, 3vw, 30px) 0 clamp(18px, 2.6vw, 26px);
}

.page-about .about-index .eyebrow {
  margin: 0;
  color: var(--c-tundra);
}

.page-about .about-index__list {
  display: flex;
  gap: 10px;
  margin: 14px 0 0;
  padding: 3px 0;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

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

.page-about .about-index__list a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 16px;
  border: 1px solid var(--line-dark);
  border-radius: var(--r-pill);
  color: var(--c-ice);
  font-size: 13px;
  white-space: nowrap;
  text-decoration: none;
  transition: background .22s ease, color .22s ease, border-color .22s ease;
}

.page-about .about-index__list a:hover,
.page-about .about-index__list a:focus-visible {
  background: var(--c-ice);
  border-color: var(--c-ice);
  color: var(--c-glacier);
}

.page-about .about-index__list .num {
  font-weight: 700;
  color: var(--c-lava);
}

.page-about .about-index__list a:hover .num {
  color: var(--c-glacier);
}

/* ---------- 章节骨架 ---------- */
.page-about .about-chapter {
  padding: clamp(52px, 7vw, 100px) 0;
  scroll-margin-top: 96px;
}

.page-about .about-chapter--alt {
  background: #FFFFFF;
  border-top: 1px solid var(--line-light);
  border-bottom: 1px solid var(--line-light);
}

.page-about .about-chapter--dark {
  background: var(--c-polar);
  color: var(--c-ice);
}

.page-about .about-chapter__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
}

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

.page-about .about-chapter .chapter__title {
  margin: 0 0 clamp(18px, 2.4vw, 28px);
  max-width: 22em;
  font-size: clamp(26px, 3.8vw, 48px);
  font-weight: 800;
  line-height: 1.14;
  letter-spacing: -.028em;
  color: var(--ink-strong);
}

.page-about .about-chapter--dark .chapter__title {
  color: var(--c-ice);
}

.page-about .about-chapter--dark .prose {
  color: var(--c-frost);
}

/* ---------- 侧边编号与竖排注释 ---------- */
.page-about .about-rail {
  display: flex;
  align-items: center;
  gap: 14px;
}

.page-about .about-rail__num {
  font-size: clamp(26px, 3vw, 40px);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -.05em;
  color: var(--c-lava);
}

.page-about .about-chapter--dark .about-rail__num {
  color: var(--c-neon);
}

.page-about .about-rail .vnote {
  display: inline-block;
  padding: 3px 0;
  font-size: 11px;
  letter-spacing: .28em;
  color: var(--c-tundra);
  background: transparent;
  border-radius: var(--r-pill);
  transition: color .25s ease, letter-spacing .25s ease, background .25s ease, padding .25s ease;
}

.page-about .about-chapter--dark .about-rail .vnote {
  color: var(--c-frost);
}

/* ---------- 分栏 ---------- */
.page-about .about-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 36px);
}

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

.page-about .about-lead {
  margin: 0 0 clamp(18px, 2.4vw, 26px);
  max-width: 36em;
  font-size: clamp(15px, 1.4vw, 17px);
  line-height: 1.85;
  color: var(--ink-soft);
}

.page-about .about-lead--dark {
  color: var(--c-frost);
}

.page-about .about-footnote {
  margin: clamp(20px, 3vw, 28px) 0 0;
  max-width: 44em;
  padding-left: 16px;
  border-left: 3px solid var(--c-lava);
  font-size: 14px;
  line-height: 1.85;
  color: var(--ink-soft);
}

.page-about .about-footnote--dark {
  color: var(--c-tundra);
}

/* ---------- 侧注卡 ---------- */
.page-about .about-note {
  align-self: start;
  padding: 20px 20px 22px;
  background: var(--c-frost);
  border-radius: var(--r-md);
}

.page-about .about-note p {
  margin: 12px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--ink);
}

.page-about .about-note p:first-child {
  margin-top: 0;
}

.page-about .about-note--line {
  background: transparent;
  border-left: 3px solid var(--c-glacier);
  border-radius: 0;
  padding: 4px 0 4px 18px;
}

.page-about .about-chapter--dark .about-note {
  background: rgba(14, 42, 71, .6);
}

.page-about .about-chapter--dark .about-note p {
  color: var(--c-frost);
}

/* ---------- 来源卡片 ---------- */
.page-about .about-sources {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 16px;
}

.page-about .about-source {
  position: relative;
  overflow: hidden;
  padding: 24px 22px 26px;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--r-lg);
  box-shadow: var(--shadow-1);
}

.page-about .about-source::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 5px;
  background: var(--c-glacier);
}

.page-about .about-source:nth-child(2)::before {
  background: var(--c-lava);
}

.page-about .about-source:nth-child(3)::before {
  background: var(--c-neon);
}

.page-about .about-source__name {
  margin: 14px 0 10px;
  font-size: 18px;
  font-weight: 700;
  letter-spacing: -.015em;
  color: var(--ink-strong);
}

.page-about .about-source__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
}

/* ---------- 校验清单 ---------- */
.page-about .about-checks {
  display: grid;
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-checks__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 16px;
  padding: 20px 20px 22px;
  background: rgba(14, 42, 71, .55);
  border: 1px solid var(--line-dark);
  border-radius: var(--r-md);
}

.page-about .about-checks__step {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  line-height: 1.2;
  color: var(--c-lava);
}

.page-about .about-checks__title {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -.01em;
  color: var(--c-ice);
}

.page-about .about-checks__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--c-frost);
}

.page-about .about-amber {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-top: clamp(20px, 2.6vw, 28px);
  padding: 16px 18px;
  background: rgba(255, 176, 32, .12);
  border: 1px solid rgba(255, 176, 32, .45);
  border-radius: var(--r-md);
}

.page-about .about-amber__dot {
  flex: 0 0 auto;
  width: 10px;
  height: 10px;
  margin-top: 7px;
  border-radius: 50%;
  background: var(--c-amber);
  box-shadow: 0 0 0 4px rgba(255, 176, 32, .18);
  animation: about-breathe 2.6s ease-in-out infinite;
}

@keyframes about-breathe {
  0%, 100% { opacity: 1; }
  50% { opacity: .4; }
}

.page-about .about-amber__text {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--c-frost);
}

.page-about .about-amber__text strong {
  color: var(--c-amber);
}

/* ---------- 图片 ---------- */
.page-about .about-photo {
  margin: 0;
}

.page-about .about-photo--wide .figure__media {
  border-radius: var(--r-lg) var(--r-lg) var(--r-sm) var(--r-sm);
  overflow: hidden;
}

.page-about .about-photo--narrow {
  align-self: start;
}

.page-about .about-photo .figure__img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  aspect-ratio: 3 / 2;
}

.page-about .about-photo--narrow .figure__img {
  aspect-ratio: 4 / 3;
}

.page-about .about-photo .figure__caption {
  margin-top: 12px;
  font-size: 12px;
  line-height: 1.7;
  color: var(--c-tundra);
}

.page-about .about-chapter--dark .about-photo .figure__caption {
  color: var(--c-tundra);
}

/* ---------- 团队条形图 ---------- */
.page-about .about-team {
  display: grid;
  gap: 18px;
  margin: clamp(22px, 3vw, 30px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-team__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  grid-template-rows: auto auto;
  align-items: center;
  gap: 8px 14px;
}

.page-about .about-team__name {
  grid-column: 1;
  grid-row: 1;
  font-size: 15px;
  font-weight: 700;
  color: var(--ink-strong);
}

.page-about .about-team__role {
  display: block;
  margin-top: 3px;
  font-size: 12px;
  font-weight: 400;
  letter-spacing: .04em;
  color: var(--c-tundra);
}

.page-about .about-team__count {
  grid-column: 2;
  grid-row: 1;
  font-size: 20px;
  font-weight: 700;
  color: var(--c-lava);
  text-align: right;
}

.page-about .about-team__bar {
  grid-column: 1 / -1;
  grid-row: 2;
  display: block;
  height: 12px;
  border-radius: var(--r-pill);
  background: var(--c-frost);
  overflow: hidden;
}

.page-about .about-team__bar i {
  display: block;
  height: 100%;
  border-radius: var(--r-pill);
  background: linear-gradient(90deg, var(--c-glacier), var(--c-tundra));
}

.page-about .about-team__row:nth-child(1) .about-team__bar i { width: 36.8%; }
.page-about .about-team__row:nth-child(2) .about-team__bar i { width: 23.7%; }
.page-about .about-team__row:nth-child(3) .about-team__bar i { width: 28.9%; }
.page-about .about-team__row:nth-child(4) .about-team__bar i { width: 10.5%; }

/* ---------- 年表 ---------- */
.page-about .about-timeline {
  margin-top: clamp(20px, 3vw, 30px);
}

.page-about .about-timeline__figure {
  position: relative;
  margin: 0 0 clamp(26px, 4vw, 44px);
  border-radius: var(--r-lg);
  overflow: hidden;
}

.page-about .about-timeline__figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  aspect-ratio: 2 / 1;
}

.page-about .about-timeline__figure::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(7, 23, 38, .15) 0%, rgba(7, 23, 38, .82) 100%);
  pointer-events: none;
}

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

.page-about .about-timeline__list::before {
  content: "";
  position: absolute;
  left: 8px;
  top: 10px;
  bottom: 18px;
  width: 2px;
  background: linear-gradient(180deg, var(--c-tundra) 0%, var(--c-lava) 62%, var(--c-neon) 100%);
  opacity: .55;
}

.page-about .about-timeline__item {
  position: relative;
  padding-left: 38px;
  padding-bottom: 14px;
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 16px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--c-polar);
  border: 2px solid var(--c-tundra);
}

.page-about .about-timeline__item:last-child {
  padding-bottom: 0;
}

.page-about .about-timeline__item:last-child::before {
  background: var(--c-lava);
  border-color: var(--c-lava);
  box-shadow: 0 0 0 5px rgba(255, 90, 31, .2);
}

.page-about .about-tl {
  border: 1px solid var(--line-dark);
  border-radius: var(--r-md);
  background: rgba(14, 42, 71, .4);
  transition: background .25s ease, border-color .25s ease;
}

.page-about .about-tl[open] {
  background: rgba(14, 42, 71, .76);
  border-color: rgba(184, 255, 60, .3);
}

.page-about .about-tl__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  padding: 14px 18px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-tl__year {
  flex: 0 0 auto;
  font-size: 21px;
  font-weight: 700;
  letter-spacing: -.02em;
  color: var(--c-lava);
}

.page-about .about-tl__title {
  flex: 1 1 auto;
  min-width: 0;
  font-size: 15px;
  font-weight: 600;
  color: var(--c-ice);
}

.page-about .about-tl__mark {
  flex: 0 0 auto;
  align-self: center;
  width: 9px;
  height: 9px;
  border-right: 2px solid var(--c-neon);
  border-bottom: 2px solid var(--c-neon);
  transform: rotate(45deg);
  transition: transform .25s ease;
}

.page-about .about-tl[open] .about-tl__mark {
  transform: rotate(-135deg);
}

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

.page-about .about-tl__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--c-frost);
}

/* ---------- 边界折叠组 ---------- */
.page-about .about-limits {
  display: grid;
  gap: 12px;
  margin-top: clamp(18px, 2.4vw, 26px);
}

.page-about .about-limit {
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: var(--bg-card);
  transition: border-color .25s ease, box-shadow .25s ease;
}

.page-about .about-limit[open] {
  border-color: rgba(255, 90, 31, .42);
  box-shadow: var(--shadow-1);
}

.page-about .about-limit__head {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 20px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .about-limit__dot {
  flex: 0 0 auto;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--c-tundra);
}

.page-about .about-limit[open] .about-limit__dot {
  background: var(--c-lava);
}

.page-about .about-limit__title {
  flex: 1 1 auto;
  min-width: 0;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: -.012em;
  color: var(--ink-strong);
}

.page-about .about-limit__mark {
  flex: 0 0 auto;
  width: 9px;
  height: 9px;
  border-right: 2px solid var(--c-glacier);
  border-bottom: 2px solid var(--c-glacier);
  transform: rotate(45deg);
  transition: transform .25s ease;
}

.page-about .about-limit[open] .about-limit__mark {
  transform: rotate(-135deg);
  border-color: var(--c-lava);
}

.page-about .about-limit__body {
  padding: 0 20px 20px 42px;
}

.page-about .about-limit__body p {
  margin: 0;
  max-width: 42em;
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-soft);
}

/* ---------- 收尾 ---------- */
.page-about .about-cta {
  padding: clamp(56px, 8vw, 104px) 0 clamp(60px, 8vw, 110px);
  background: linear-gradient(135deg, var(--c-glacier) 0%, var(--c-moss) 100%);
  color: var(--c-ice);
}

.page-about .about-cta .eyebrow {
  margin: 0 0 16px;
  color: var(--c-neon);
}

.page-about .about-cta__title {
  margin: 0;
  max-width: 18em;
  font-size: clamp(26px, 4vw, 52px);
  font-weight: 800;
  line-height: 1.12;
  letter-spacing: -.03em;
  color: var(--c-ice);
}

.page-about .about-cta__lead {
  margin: clamp(16px, 2.4vw, 24px) 0 0;
  max-width: 38em;
  font-size: clamp(15px, 1.4vw, 17px);
  line-height: 1.85;
  color: var(--c-frost);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(24px, 3.4vw, 38px);
}

.page-about .about-cta .btn--ghost {
  color: var(--c-ice);
  border-color: var(--line-dark);
}

.page-about .about-cta__foot {
  margin: clamp(26px, 4vw, 40px) 0 0;
  padding-top: 22px;
  border-top: 1px solid var(--line-dark);
  max-width: 46em;
  font-size: 13px;
  line-height: 1.9;
  color: var(--c-tundra);
}

.page-about .about-cta__foot a {
  color: var(--c-ice);
  text-decoration: none;
  border-bottom: 1px solid var(--c-lava);
  padding-bottom: 1px;
}

.page-about .about-cta__foot a:hover {
  color: var(--c-lava);
}

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

  .page-about .about-hero__meta {
    gap: 22px 28px;
  }

  .page-about .about-team__row {
    grid-template-columns: minmax(150px, 210px) minmax(0, 1fr) auto;
    grid-template-rows: auto;
    gap: 18px;
  }

  .page-about .about-team__name { grid-column: 1; grid-row: 1; }
  .page-about .about-team__bar { grid-column: 2; grid-row: 1; }
  .page-about .about-team__count { grid-column: 3; grid-row: 1; }
}

@media (min-width: 820px) {
  .page-about .about-sources {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

  .page-about .about-chapter__grid {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(26px, 3.4vw, 56px);
  }

  .page-about .about-rail {
    position: sticky;
    top: 104px;
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
  }

  .page-about .about-rail .vnote {
    writing-mode: vertical-rl;
    text-orientation: mixed;
  }

  .page-about .about-rail .vnote:hover,
  .page-about .about-rail .vnote:focus-visible {
    writing-mode: horizontal-tb;
    letter-spacing: .06em;
    padding: 4px 10px;
    background: var(--c-frost);
    color: var(--c-glacier);
    white-space: nowrap;
    position: relative;
    z-index: 2;
  }

  .page-about .about-chapter--dark .about-rail .vnote:hover,
  .page-about .about-chapter--dark .about-rail .vnote:focus-visible {
    background: var(--c-glacier);
    color: var(--c-ice);
  }

  .page-about .about-split--75 {
    grid-template-columns: 7fr 5fr;
    align-items: start;
  }

  .page-about .about-split--57 {
    grid-template-columns: 5fr 7fr;
    align-items: start;
  }

  .page-about .about-timeline__list::before {
    left: 9px;
  }

  .page-about .about-timeline__item {
    padding-left: 46px;
    padding-bottom: 16px;
  }

  .page-about .about-timeline__item::before {
    left: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-amber__dot {
    animation: none;
  }

  .page-about .about-rail .vnote,
  .page-about .about-tl__mark,
  .page-about .about-limit__mark,
  .page-about .about-limit,
  .page-about .about-tl {
    transition: none;
  }
}