.page-about {
  --about-sec: clamp(38px, 6.5vw, 78px);
  padding-bottom: clamp(40px, 8vw, 96px);
}

.page-about .about-body {
  display: block;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 4vw, 40px);
  padding-block: clamp(24px, 5vw, 60px) clamp(32px, 5.5vw, 64px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero__title {
  margin: 14px 0 0;
  font-size: var(--fs-display);
  line-height: var(--lh-tight);
  letter-spacing: -.02em;
  color: var(--paper);
}

.page-about .about-hero__lead {
  max-width: 30em;
  margin: clamp(16px, 3vw, 26px) 0 0;
  color: var(--mist);
}

.page-about .about-hero__aside {
  display: flex;
  align-items: flex-end;
  justify-content: flex-start;
}

.page-about .about-hero__aside .vert-note {
  writing-mode: horizontal-tb;
  transform: none;
  font-size: var(--fs-micro);
  letter-spacing: .16em;
  color: var(--muted);
}

/* ---------- 首屏数据条 ---------- */
.page-about .about-facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: clamp(26px, 4vw, 44px);
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .about-facts__cell {
  padding: 15px 14px;
  background: var(--deep);
}

.page-about .about-facts__num {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(1.5rem, 4vw, 2.2rem);
  line-height: 1.1;
  color: var(--cyan);
}

.page-about .about-facts__label {
  display: block;
  margin-top: 7px;
  font-size: var(--fs-label);
  letter-spacing: .16em;
  color: var(--muted);
}

/* ---------- 章节骨架 ---------- */
.page-about .chapter {
  padding-block: var(--about-sec);
  border-top: 1px solid var(--line);
}

.page-about .chapter__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px 18px;
  align-items: start;
  margin-bottom: clamp(18px, 3.2vw, 34px);
}

.page-about .chapter__num {
  font-size: clamp(1.9rem, 6.5vw, 3.4rem);
  font-weight: 700;
  line-height: .86;
  color: rgba(127, 163, 184, .3);
  -webkit-text-stroke: 1px rgba(34, 211, 238, .38);
}

.page-about .chapter__meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 18px;
}

.page-about .chapter__title {
  margin: 0;
  font-size: var(--fs-h2);
  line-height: 1.28;
  color: var(--paper);
}

.page-about .chapter__tag {
  margin: 0;
  font-size: var(--fs-micro);
  letter-spacing: .16em;
  color: var(--muted);
}

.page-about .chapter__body > * + * {
  margin-top: 1.05em;
}

.page-about .chapter__body .prose {
  margin-inline: 0;
}

/* ---------- 三层口径列表 ---------- */
.page-about .layer-list {
  list-style: none;
  margin: clamp(22px, 3.5vw, 34px) 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.page-about .layer-list__item {
  display: grid;
  gap: 7px 22px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.page-about .layer-list__key {
  font-size: var(--fs-small);
  letter-spacing: .1em;
}

.page-about .layer-list__val {
  color: var(--mist);
  font-size: var(--fs-small);
  line-height: 1.85;
}

/* ---------- 图像容器 ---------- */
.page-about .about-fig {
  margin: clamp(24px, 4vw, 40px) 0 0;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

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

.page-about .about-fig--wide img {
  aspect-ratio: 16 / 9;
}

.page-about .about-fig--team img {
  aspect-ratio: 4 / 3;
}

.page-about .about-fig--band {
  margin-block: clamp(10px, 2vw, 22px) 0;
}

.page-about .about-fig--band img {
  aspect-ratio: 10 / 3;
}

.page-about .about-fig__cap {
  padding: 11px 14px;
  border-top: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: var(--fs-micro);
  letter-spacing: .1em;
  color: var(--muted);
  background: var(--glass-soft);
}

/* ---------- 版本阶梯 ---------- */
.page-about .ladder {
  margin-top: clamp(24px, 4vw, 40px);
  border-top: 1px solid var(--line);
}

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

.page-about .ladder__step .fold__btn {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  gap: 10px 16px;
  align-items: center;
  width: 100%;
  padding: 16px 14px;
  border: 0;
  border-left: 2px solid transparent;
  background: transparent;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
  transition: background-color 160ms ease, border-color 160ms ease;
}

.page-about .ladder__step .fold__btn:hover,
.page-about .ladder__step .fold__btn:focus-visible {
  background: var(--glass-soft);
  border-left-color: var(--cyan);
}

.page-about .ladder__ver {
  font-size: clamp(1.05rem, 2.6vw, 1.5rem);
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--paper);
}

.page-about .ladder__sum {
  font-size: var(--fs-small);
  line-height: 1.7;
  color: var(--mist);
}

.page-about .ladder__step .fold__panel {
  padding: 2px 14px 20px;
}

.page-about .ladder__step .fold__panel .prose {
  margin: 0;
  font-size: var(--fs-small);
  color: var(--muted);
  line-height: 1.85;
}

/* ---------- 非对称双列 ---------- */
.page-about .about-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(22px, 4vw, 44px);
  align-items: start;
  margin-top: clamp(22px, 3.5vw, 36px);
}

/* ---------- 维护分工 ---------- */
.page-about .crew {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.page-about .crew__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 4px 18px;
  align-items: baseline;
  padding: 18px 12px;
  border-bottom: 1px solid var(--line);
  border-left: 2px solid transparent;
  transition: background-color 160ms ease, border-color 160ms ease;
}

.page-about .crew__row:hover,
.page-about .crew__row:focus-within {
  background: var(--glass-soft);
  border-left-color: var(--violet);
}

.page-about .crew__name {
  font-size: var(--fs-h3);
  font-weight: 600;
  color: var(--paper);
}

.page-about .crew__count {
  font-size: clamp(1.25rem, 3vw, 1.7rem);
  color: var(--cyan);
}

.page-about .crew__duty {
  grid-column: 1 / -1;
  font-size: var(--fs-small);
  line-height: 1.85;
  color: var(--mist);
}

.page-about .crew__foot {
  margin-top: clamp(18px, 3vw, 28px);
  font-size: var(--fs-small);
  color: var(--muted);
}

/* ---------- 校准与复核 ---------- */
.page-about .cycle {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: clamp(24px, 4vw, 36px);
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .cycle__item {
  padding: clamp(20px, 3.2vw, 30px);
  background: var(--panel);
  border-left: 3px solid var(--cyan);
}

.page-about .cycle__item--quarter {
  border-left-color: var(--violet);
}

.page-about .cycle__freq {
  margin: 0;
  color: var(--muted);
}

.page-about .cycle__title {
  margin: 10px 0 0;
  font-size: var(--fs-h3);
  color: var(--paper);
}

.page-about .cycle__body {
  margin: 10px 0 0;
  font-size: var(--fs-small);
  line-height: 1.85;
  color: var(--mist);
}

/* ---------- 地域范围 ---------- */
.page-about .geo__claim {
  margin: 0;
  padding-left: clamp(16px, 3vw, 24px);
  border-left: 2px solid var(--cyan);
  font-size: clamp(1.12rem, 2.6vw, 1.6rem);
  line-height: 1.6;
  color: var(--paper);
}

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

.page-about .geo__rules li {
  padding: 13px 0;
  border-bottom: 1px solid var(--line);
  font-size: var(--fs-small);
  line-height: 1.85;
  color: var(--mist);
}

.page-about .geo__rules li:first-child {
  padding-top: 0;
}

/* ---------- 字段表 ---------- */
.page-about .data-caption {
  padding: 0 0 12px;
  text-align: left;
  color: var(--muted);
}

.page-about .chapter .table-wrap {
  margin-top: clamp(22px, 3.5vw, 34px);
}

/* ---------- 结尾索引 ---------- */
.page-about .about-next {
  border-top: 1px solid var(--line);
}

.page-about .about-next .h3 {
  margin: 0 0 18px;
  color: var(--paper);
}

.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 12px;
}

/* ---------- 媒体查询 ---------- */
@media (min-width: 720px) {
  .page-about .about-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .layer-list__item {
    grid-template-columns: minmax(118px, 170px) minmax(0, 1fr);
    align-items: baseline;
  }

  .page-about .cycle {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .ladder__step:nth-child(2) .fold__btn {
    padding-left: 40px;
  }

  .page-about .ladder__step:nth-child(3) .fold__btn {
    padding-left: 66px;
  }

  .page-about .ladder__step:nth-child(4) .fold__btn {
    padding-left: 92px;
  }

  .page-about .ladder__step:nth-child(2) .fold__panel {
    padding-left: 40px;
  }

  .page-about .ladder__step:nth-child(3) .fold__panel {
    padding-left: 66px;
  }

  .page-about .ladder__step:nth-child(4) .fold__panel {
    padding-left: 92px;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: end;
    column-gap: clamp(24px, 4vw, 56px);
  }

  .page-about .about-hero__aside {
    justify-content: flex-end;
    padding-bottom: 8px;
  }

  .page-about .about-hero__aside .vert-note {
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    font-size: var(--fs-label);
  }

  .page-about .chapter__head {
    grid-template-columns: minmax(88px, 140px) minmax(0, 1fr);
    gap: 20px 26px;
    align-items: center;
  }

  .page-about .chapter__num {
    font-size: clamp(2.6rem, 4.6vw, 4.2rem);
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
  }
}