.page-about {
  --about-rail: 54px;
  --about-gap: 14px;
  padding: 14px 0 72px;
}

.page-about .breadcrumb {
  margin-bottom: 18px;
}

/* ---------- 页面开场 ---------- */

.page-about .about-head {
  max-width: 100%;
  padding-bottom: 4px;
}

.page-about .about-head__title {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: clamp(30px, 7.4vw, 52px);
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--tile-900);
  margin: 12px 0 0;
  max-width: 18ch;
}

.page-about .about-head__lede {
  max-width: 62ch;
  margin-top: 18px;
  font-size: 17px;
  line-height: 1.8;
  color: var(--ink-600);
}

.page-about .about-head__marks {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px 20px;
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px solid var(--tile-300);
}

.page-about .about-mark {
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: 14px;
  line-height: 1.5;
  color: var(--ink-400);
}

.page-about .about-mark b {
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: 30px;
  line-height: 1.1;
  color: var(--amber-500);
  letter-spacing: -0.03em;
}

.page-about .about-lead-figure {
  margin: 34px 0 0;
}

/* ---------- 编号档案区 ---------- */

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

.page-about .about-eyebrow {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--mint-500);
  margin: 0 0 8px;
}

.page-about .about-archive__head {
  max-width: 64ch;
}

.page-about .about-path {
  list-style: none;
  margin: 36px 0 0;
  padding: 0;
  display: block;
}

.page-about .about-step {
  position: relative;
  display: grid;
  grid-template-columns: var(--about-rail) minmax(0, 1fr);
  column-gap: var(--about-gap);
  padding: 30px 0;
  scroll-margin-top: calc(var(--header-h) + 28px);
}

.page-about .about-step::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: calc(var(--about-rail) / 2);
  width: 1px;
  background: var(--tile-300);
}

.page-about .about-step:last-child::before {
  bottom: 62%;
}

.page-about .about-step__rail {
  position: relative;
  z-index: 1;
  display: flex;
  justify-content: center;
  align-items: flex-start;
}

.page-about .about-step__num {
  display: block;
  padding: 2px 6px 8px;
  background: var(--paper-100);
  font-family: var(--font-mono);
  font-weight: 500;
  font-size: clamp(30px, 5.6vw, 54px);
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--tile-300);
  text-align: center;
  transition: color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .about-step[data-active] .about-step__num {
  color: var(--amber-500);
  transform: translateY(-2px) scale(1.04);
}

.page-about .about-step__title {
  position: relative;
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 21px;
  line-height: 1.4;
  color: var(--tile-900);
  margin: 0 0 16px;
  padding-bottom: 12px;
}

.page-about .about-step__title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 72px;
  height: 2px;
  background: linear-gradient(90deg, var(--tile-600), var(--mint-150));
  border-radius: 2px;
}

.page-about .about-step__text {
  max-width: 62ch;
  margin: 0 0 13px;
  font-size: 16px;
  line-height: 1.82;
  color: var(--ink-600);
}

.page-about .about-step__text:last-of-type {
  margin-bottom: 0;
}

/* ---------- 数据小表 ---------- */

.page-about .about-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 24px;
  margin: 22px 0 0;
  padding: 0;
  border-top: 1px solid var(--tile-300);
  max-width: 660px;
}

.page-about .about-facts > div {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  padding: 12px 0;
  border-bottom: 1px solid var(--blue-050);
}

.page-about .about-facts dt {
  font-size: 13px;
  line-height: 1.5;
  color: var(--ink-400);
  letter-spacing: 0.01em;
}

.page-about .about-facts dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 17px;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
  color: var(--tile-900);
  text-align: right;
}

/* ---------- 团队构成条 ---------- */

.page-about .about-team-wrap {
  display: grid;
  gap: 24px;
  margin-top: 22px;
}

.page-about .about-team {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(132px, 1fr));
  gap: 12px;
  align-content: start;
}

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

.page-about .about-team__sum {
  list-style: none;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 14px 14px 12px;
  background: var(--paper-100);
  border: 1px solid var(--tile-300);
  border-radius: 12px;
  transition: border-color var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}

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

.page-about .about-team__sum:hover {
  border-color: var(--tile-600);
  box-shadow: var(--shadow-soft);
}

.page-about .about-team__sum:focus-visible {
  outline: 2px solid var(--amber-500);
  outline-offset: 3px;
}

.page-about .about-team__bar {
  display: block;
  width: 100%;
  height: 7px;
  border-radius: 4px;
  background: var(--tile-300);
}

.page-about .about-team__node:nth-child(1) .about-team__bar {
  background: var(--tile-600);
}

.page-about .about-team__node:nth-child(2) .about-team__bar {
  background: var(--mint-500);
}

.page-about .about-team__node:nth-child(3) .about-team__bar {
  background: var(--amber-500);
}

.page-about .about-team__node:nth-child(4) .about-team__bar {
  background: var(--tile-300);
}

.page-about .about-team__name {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 17px;
  line-height: 1.4;
  color: var(--tile-900);
}

.page-about .about-team__node[open] .about-team__sum {
  border-color: var(--tile-600);
  background: var(--paper-100);
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
  box-shadow: var(--shadow-soft);
}

.page-about .about-team__desc {
  margin: 0;
  padding: 14px 16px 16px;
  background: var(--blue-050);
  border: 1px solid var(--tile-600);
  border-top: 0;
  border-bottom-left-radius: 12px;
  border-bottom-right-radius: 12px;
  font-size: 15px;
  line-height: 1.72;
  color: var(--ink-600);
}

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

/* ---------- 版本对照 ---------- */

.page-about .about-version-table {
  margin: 24px 0 0;
}

.page-about .about-version-table__caption {
  caption-side: top;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--mint-500);
  padding-bottom: 10px;
}

.page-about .about-device-figure {
  margin: 26px 0 0;
}

/* ---------- 结尾提示 ---------- */

.page-about .about-cta {
  margin-top: 24px;
  max-width: 62ch;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 16px 0 0;
}

/* ---------- 右侧悬浮阶段索引 ---------- */

.page-about .about-jump {
  display: none;
}

.page-about .about-jump__link {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 30px;
  border: 1px solid var(--tile-300);
  border-radius: 8px;
  background: var(--paper-100);
  color: var(--ink-400);
  text-decoration: none;
  font-size: 13px;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-jump__link:hover,
.page-about .about-jump__link:focus-visible {
  color: var(--paper-100);
  background: var(--amber-500);
  border-color: var(--amber-500);
}

/* ---------- 响应式 ---------- */

@media (min-width: 640px) {
  .page-about .about-head__marks {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (min-width: 900px) {
  .page-about {
    --about-rail: 104px;
    --about-gap: 26px;
    padding-bottom: 96px;
  }

  .page-about .about-lead-figure {
    max-width: 88%;
    margin-left: auto;
  }

  .page-about .about-archive {
    margin-top: 72px;
  }

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

  .page-about .about-step__title {
    font-size: 25px;
  }

  .page-about .about-team-wrap {
    grid-template-columns: minmax(0, 1.5fr) minmax(0, 0.6fr);
    align-items: start;
    gap: 28px;
  }

  .page-about .about-device-figure {
    max-width: 74%;
  }

  .page-about .about-path {
    margin-top: 44px;
  }
}

@media (min-width: 1360px) {
  .page-about .about-jump {
    display: flex;
    flex-direction: column;
    gap: 8px;
    position: fixed;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 20;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-step__num,
  .page-about .about-team__sum,
  .page-about .about-jump__link {
    transition: none;
  }

  .page-about .about-step[data-active] .about-step__num {
    transform: none;
  }
}