.page-about {
  background: var(--paper);
  color: var(--charcoal);
  font-family: var(--font-body);
  overflow-x: hidden;
}

.page-about .container {
  padding-left: var(--shell-pad);
  padding-right: var(--shell-pad);
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  padding: 20px 0 0;
}
.page-about .about-crumb__link {
  color: var(--rock);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .2s var(--ease), border-color .2s var(--ease);
}
.page-about .about-crumb__link:hover,
.page-about .about-crumb__link:focus-visible {
  color: var(--signal);
  border-bottom-color: var(--signal);
}
.page-about .about-crumb__sep { color: var(--rock); opacity: .6; }
.page-about .about-crumb__now { color: var(--ink-moss); }

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-bottom: clamp(28px, 5vw, 56px);
  border-bottom: 1px solid var(--line-on-paper);
}
.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: linear-gradient(to right, rgba(11, 43, 35, .06) 1px, transparent 1px);
  background-size: 12.5% 100%;
  pointer-events: none;
}
.page-about .about-hero__grid {
  position: relative;
  display: grid;
  gap: 30px;
  padding-top: clamp(24px, 4vw, 44px);
}
.page-about .about-hero__kicker {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--rock);
}
.page-about .about-hero__kicker::before {
  content: "";
  display: inline-block;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--signal);
  margin-right: 9px;
  vertical-align: 1px;
}
.page-about .about-hero__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(30px, 7vw, 58px);
  line-height: 1.04;
  letter-spacing: -.02em;
  color: var(--ink-moss);
}
.page-about .about-hero__lede {
  margin: 20px 0 0;
  max-width: 34em;
  font-size: var(--step-2);
  line-height: 1.8;
  color: rgba(23, 28, 26, .8);
}
.page-about .about-hero__aside {
  border-top: 1px solid var(--line-on-paper);
  padding-top: 16px;
}
.page-about .about-hero__aside-note {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--rock);
}
.page-about .about-stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px 14px;
}
.page-about .about-stats__item {
  display: flex;
  flex-direction: column;
  gap: 3px;
  border-left: 1px solid var(--line-on-paper);
  padding-left: 10px;
}
.page-about .about-stats__num {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--step-4);
  line-height: 1;
  letter-spacing: -.01em;
  color: var(--ink-moss);
}
.page-about .about-stats__unit {
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 500;
  margin-left: 3px;
  color: var(--rock);
}
.page-about .about-stats__label {
  font-size: 12px;
  color: var(--rock);
}

/* ---------- 章节头 ---------- */
.page-about .about-sec-head {
  display: grid;
  gap: 9px;
  padding-top: 16px;
  border-top: 1px solid var(--line-on-paper);
  margin-bottom: clamp(24px, 4vw, 42px);
}
.page-about .about-sec-head__num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--terracotta);
}
.page-about .about-sec-head__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(23px, 4.4vw, 34px);
  line-height: 1.14;
  letter-spacing: -.02em;
  color: var(--ink-moss);
}
.page-about .about-sec-head__note {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--rock);
}

/* ---------- 时间线 ---------- */
.page-about .about-timeline {
  padding: clamp(34px, 6vw, 74px) 0;
  border-bottom: 1px solid var(--line-on-paper);
}
.page-about .about-timeline__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 22px;
}
.page-about .year-rail {
  position: sticky;
  top: calc(var(--topbar-h) + 10px);
  z-index: 3;
  background: var(--paper);
  padding-bottom: 4px;
  margin: 0 calc(var(--shell-pad) * -1);
  padding-left: var(--shell-pad);
  padding-right: var(--shell-pad);
}
.page-about .year-rail__list {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
}
.page-about .year-rail__list::-webkit-scrollbar { display: none; }
.page-about .year-rail__link {
  display: flex;
  align-items: baseline;
  gap: 7px;
  padding: 7px 14px;
  border: 1px solid var(--line-on-paper);
  border-radius: 999px;
  text-decoration: none;
  white-space: nowrap;
  color: var(--rock);
  transition: color .2s var(--ease), border-color .2s var(--ease), background-color .2s var(--ease);
}
.page-about .year-rail__year {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .04em;
}
.page-about .year-rail__label { font-size: 12px; }
.page-about .year-rail__link:hover,
.page-about .year-rail__link:focus-visible {
  color: var(--ink-moss);
  border-color: var(--signal);
}
.page-about .year-rail__link[aria-current="true"] {
  color: var(--ink-moss);
  border-color: var(--signal);
  background: rgba(255, 107, 44, .08);
}

.page-about .stage {
  position: relative;
  padding-left: 18px;
  border-left: 1px solid var(--terracotta);
  margin-bottom: clamp(30px, 5vw, 54px);
}
.page-about .stage:last-child { margin-bottom: 0; }
.page-about .stage__meta {
  margin: 0 0 8px;
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--terracotta);
}
.page-about .stage__index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 22px;
  height: 18px;
  padding: 0 5px;
  background: var(--terracotta);
  color: var(--paper);
  font-size: 11px;
  letter-spacing: .02em;
}
.page-about .stage__title {
  margin: 0 0 12px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(21px, 3.4vw, 28px);
  line-height: 1.22;
  letter-spacing: -.015em;
  color: var(--ink-moss);
}
.page-about .stage__lede {
  margin: 0;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(23, 28, 26, .8);
}
.page-about .stage__points {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: grid;
  gap: 9px;
}
.page-about .stage__points li {
  position: relative;
  padding-left: 17px;
  font-size: 14.5px;
  line-height: 1.7;
  color: rgba(23, 28, 26, .74);
}
.page-about .stage__points li::before {
  content: "";
  position: absolute;
  left: 0;
  top: .68em;
  width: 8px;
  height: 1px;
  background: var(--rock);
}

/* ---------- 折叠面板 ---------- */
.page-about .fold {
  margin-top: 18px;
  border: 1px solid var(--line-on-paper);
  background: rgba(227, 230, 225, .45);
}
.page-about .fold__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  width: 100%;
  padding: 12px 14px;
  border: 0;
  background: none;
  font: inherit;
  text-align: left;
  color: var(--ink-moss);
  cursor: pointer;
}
.page-about .fold__head:focus-visible {
  outline: 1px solid var(--signal);
  outline-offset: 2px;
}
.page-about .fold__title {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .05em;
  line-height: 1.6;
  color: var(--rock);
}
.page-about .fold__head:hover .fold__title { color: var(--ink-moss); }
.page-about .fold__icon {
  position: relative;
  flex: none;
  width: 12px;
  height: 12px;
}
.page-about .fold__icon::before,
.page-about .fold__icon::after {
  content: "";
  position: absolute;
  background: var(--signal);
  transition: transform .22s var(--ease), opacity .22s var(--ease);
}
.page-about .fold__icon::before { left: 0; top: 5.5px; width: 12px; height: 1px; }
.page-about .fold__icon::after { left: 5.5px; top: 0; width: 1px; height: 12px; }
.page-about .fold[data-open="true"] .fold__icon::after { transform: scaleY(0); opacity: 0; }
.page-about .fold__body { display: none; }
.page-about .fold[data-open="true"] .fold__body { display: block; }
.page-about .fold__inner {
  padding: 0 14px 14px;
  border-top: 1px solid var(--line-on-paper);
}
.page-about .fold__inner p {
  margin: 12px 0 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(23, 28, 26, .78);
}

/* ---------- 线框结构图 ---------- */
.page-about .wire {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 14px;
}
.page-about .wire__cell {
  flex: 1 1 46px;
  min-height: 44px;
  border: 1px solid var(--line-on-paper);
  background: rgba(245, 242, 233, .9);
}
.page-about .wire__cell--full { flex-basis: 100%; }
.page-about .wire__cell--accent {
  border-color: rgba(46, 211, 192, .6);
  background: rgba(46, 211, 192, .12);
}
.page-about .wire__caption {
  margin: 10px 0 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .04em;
  color: var(--rock);
}

/* ---------- 结构演进（深色区） ---------- */
.page-about .about-arc {
  background: var(--ink-moss);
  color: var(--ink-1);
  padding: clamp(34px, 6vw, 78px) 0;
}
.page-about .about-arc__grid {
  display: grid;
  gap: 28px;
}
.page-about .about-arc__figure { margin: 0; }
.page-about .about-arc__figure img {
  display: block;
  width: 100%;
  max-width: 340px;
  height: auto;
  border: 1px solid var(--line-on-ink);
  object-fit: cover;
}
.page-about .about-arc__caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .04em;
  line-height: 1.7;
  color: var(--ink-3);
}
.page-about .about-arc__title {
  margin: 0 0 16px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(23px, 4.4vw, 34px);
  line-height: 1.16;
  letter-spacing: -.02em;
  color: var(--paper);
}
.page-about .about-arc__para {
  margin: 0 0 14px;
  font-size: 15.5px;
  line-height: 1.85;
  color: var(--ink-2);
}
.page-about .about-arc__link {
  display: inline-block;
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .05em;
  color: var(--fluoro);
  text-decoration: none;
  border-bottom: 1px solid rgba(46, 211, 192, .45);
  padding-bottom: 2px;
  transition: color .2s var(--ease), border-color .2s var(--ease);
}
.page-about .about-arc__link:hover,
.page-about .about-arc__link:focus-visible {
  color: var(--signal-soft);
  border-bottom-color: var(--signal-soft);
}

/* ---------- 栏目清单 ---------- */
.page-about .about-columns {
  padding: clamp(34px, 6vw, 74px) 0;
  border-bottom: 1px solid var(--line-on-paper);
}
.page-about .columns-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line-on-paper);
}
.page-about .columns-list__item {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  column-gap: 12px;
  row-gap: 6px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line-on-paper);
}
.page-about .columns-list__num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .04em;
  color: var(--terracotta);
  padding-top: 5px;
}
.page-about .columns-list__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: var(--step-3);
  line-height: 1.3;
  letter-spacing: -.01em;
  color: var(--ink-moss);
}
.page-about .columns-list__text {
  grid-column: 2;
  margin: 0;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(23, 28, 26, .76);
}

/* ---------- 团队 ---------- */
.page-about .about-team {
  background: rgba(227, 230, 225, .55);
  padding: clamp(34px, 6vw, 74px) 0;
  border-bottom: 1px solid var(--line-on-paper);
}
.page-about .about-team__grid {
  display: grid;
  gap: 28px;
}
.page-about .about-team .about-sec-head { border-top-color: rgba(11, 43, 35, .18); }
.page-about .about-team__para {
  margin: 0 0 20px;
  font-size: 15.5px;
  line-height: 1.85;
  color: rgba(23, 28, 26, .8);
}
.page-about .team-roles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}
.page-about .team-roles__item {
  display: grid;
  gap: 3px;
  padding: 12px 14px;
  background: var(--paper);
  border-left: 2px solid var(--deep-fern);
}
.page-about .team-roles__item:nth-child(3) { border-left-color: var(--signal); }
.page-about .team-roles__name {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .03em;
  color: var(--ink-moss);
}
.page-about .team-roles__desc {
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--rock);
}
.page-about .about-team__figure { margin: 0; }
.page-about .about-team__figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line-on-paper);
  object-fit: cover;
}
.page-about .about-team__caption {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .04em;
  color: var(--rock);
}

/* ---------- 复核节拍 ---------- */
.page-about .about-cadence {
  padding: clamp(34px, 6vw, 74px) 0;
  border-bottom: 1px solid var(--line-on-paper);
}
.page-about .cadence-grid {
  display: grid;
  gap: 28px;
}
.page-about .cadence-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}
.page-about .cadence-list__item {
  display: grid;
  gap: 5px;
  padding: 15px 0 15px 18px;
  border-left: 1px solid var(--line-on-paper);
  position: relative;
}
.page-about .cadence-list__item::before {
  content: "";
  position: absolute;
  left: -3.5px;
  top: 22px;
  width: 6px;
  height: 6px;
  background: var(--fluoro);
}
.page-about .cadence-list__when {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .06em;
  color: var(--ink-moss);
}
.page-about .cadence-list__what {
  font-size: 14.5px;
  line-height: 1.78;
  color: rgba(23, 28, 26, .76);
}
.page-about .about-cadence__figure { margin: 0; }
.page-about .about-cadence__figure img {
  display: block;
  width: 100%;
  max-width: 320px;
  height: auto;
  object-fit: contain;
}
.page-about .about-cadence__caption {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .04em;
  color: var(--rock);
}

/* ---------- 取舍 ---------- */
.page-about .about-choice {
  padding: clamp(34px, 6vw, 74px) 0;
  background: rgba(227, 230, 225, .4);
  border-bottom: 1px solid var(--line-on-paper);
}
.page-about .about-choice .fold {
  background: var(--paper);
  margin-top: 0;
  margin-bottom: 10px;
}
.page-about .about-choice .fold__title {
  font-family: var(--font-body);
  font-size: 15px;
  letter-spacing: 0;
  color: var(--ink-moss);
}
.page-about .container--narrow {
  max-width: 780px;
  margin: 0 auto;
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  background: var(--ink-moss);
  padding: clamp(34px, 6vw, 72px) 0;
}
.page-about .about-next__grid {
  display: grid;
  gap: 24px;
}
.page-about .about-next__title {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(23px, 4.4vw, 34px);
  line-height: 1.16;
  letter-spacing: -.02em;
  color: var(--paper);
}
.page-about .about-next__para {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-2);
}
.page-about .about-next__links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-on-ink);
  border: 1px solid var(--line-on-ink);
}
.page-about .about-next__link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 16px 18px;
  background: var(--ink-moss);
  color: var(--ink-1);
  text-decoration: none;
  font-size: 15px;
  transition: background-color .2s var(--ease), color .2s var(--ease);
}
.page-about .about-next__link:hover,
.page-about .about-next__link:focus-visible {
  background: var(--deep-fern);
  color: var(--paper);
}
.page-about .about-next__arrow {
  font-family: var(--font-mono);
  color: var(--signal);
  transition: transform .2s var(--ease);
}
.page-about .about-next__link:hover .about-next__arrow,
.page-about .about-next__link:focus-visible .about-next__arrow {
  transform: translateX(4px);
}

/* ---------- 平板与桌面 ---------- */
@media (min-width: 720px) {
  .page-about .about-team__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, .86fr);
    align-items: start;
  }
  .page-about .cadence-grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, .72fr);
    align-items: start;
  }
  .page-about .about-stats { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .page-about .columns-list__item { grid-template-columns: 44px minmax(0, 1fr) minmax(0, 1.1fr); }
  .page-about .columns-list__text { grid-column: 3; }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    column-gap: clamp(28px, 5vw, 72px);
    align-items: end;
  }
  .page-about .about-timeline__grid {
    grid-template-columns: 152px minmax(0, 1fr);
    column-gap: clamp(24px, 4vw, 56px);
    align-items: start;
  }
  .page-about .year-rail {
    top: 90px;
    margin: 0;
    padding-left: 0;
    padding-right: 0;
  }
  .page-about .year-rail__list {
    flex-direction: column;
    overflow: visible;
    gap: 2px;
    padding-bottom: 0;
  }
  .page-about .year-rail__link {
    flex-direction: column;
    align-items: flex-start;
    gap: 1px;
    border-radius: 0;
    border: 0;
    border-left: 1px solid var(--line-on-paper);
    padding: 8px 0 8px 14px;
    white-space: normal;
  }
  .page-about .year-rail__link:hover,
  .page-about .year-rail__link:focus-visible {
    border-left-color: var(--signal);
    color: var(--ink-moss);
    background: none;
  }
  .page-about .year-rail__link[aria-current="true"] {
    border-left-width: 2px;
    border-left-color: var(--signal);
    background: none;
  }
  .page-about .about-arc__grid {
    grid-template-columns: minmax(0, 320px) minmax(0, 1fr);
    column-gap: clamp(32px, 6vw, 84px);
    align-items: center;
  }
  .page-about .about-arc__figure img { max-width: none; }
  .page-about .about-next__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
    column-gap: clamp(28px, 5vw, 72px);
    align-items: center;
  }
}

@media (min-width: 1100px) {
  .page-about .stage { padding-left: 26px; }
  .page-about .stage__lede { font-size: 17px; }
  .page-about .stage__points li { font-size: 15px; }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-next__arrow,
  .page-about .fold__icon::before,
  .page-about .fold__icon::after,
  .page-about .about-crumb__link,
  .page-about .year-rail__link {
    transition: none;
  }
}