.page-about {
  --about-rail: 178px;
  --about-aside: 188px;
  --about-line: rgba(30, 122, 107, 0.30);
  background: var(--c-paper);
  color: var(--c-ink);
}

/* ---------- 卷首 ---------- */
.page-about .about-masthead {
  padding: 20px 0 0;
  background:
    linear-gradient(180deg, rgba(30, 122, 107, 0.10) 0%, rgba(247, 250, 249, 0) 68%),
    var(--c-paper);
  border-bottom: var(--hair);
}

.page-about .about-masthead__inner {
  display: grid;
  gap: 18px;
  padding-bottom: 30px;
}

.page-about .about-masthead__title {
  margin: 0;
  max-width: 20em;
  font-size: clamp(30px, 6.6vw, 58px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  font-weight: 900;
  color: var(--c-green-deep);
}

.page-about .about-masthead__lede {
  margin: 0;
  max-width: 40em;
  font-size: 17px;
  line-height: 1.75;
  color: var(--c-ink);
}

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

.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 6px 0 0;
  padding: 1px;
  background: rgba(38, 51, 59, 0.14);
  border: var(--hair);
}

.page-about .about-stats__cell {
  background: var(--c-paper);
  padding: 13px 15px 15px;
}

.page-about .about-stats__key {
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--c-ink-mid);
}

.page-about .about-stats__val {
  margin: 6px 0 0;
  font-family: var(--font-mono);
  font-size: clamp(22px, 5vw, 30px);
  line-height: 1.05;
  letter-spacing: 0.02em;
  color: var(--c-amber);
}

.page-about .about-cover {
  margin: 0;
  border-top: var(--hair);
  background: var(--c-green-mist);
  line-height: 0;
  overflow: hidden;
}

.page-about .about-cover__img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 7;
  object-fit: cover;
}

/* ---------- 主体骨架 ---------- */
.page-about .about-shell {
  display: grid;
  gap: 28px;
  padding-top: 34px;
  padding-bottom: 60px;
}

.page-about .about-rail {
  border: var(--hair);
  background: var(--c-green-mist);
  padding: 8px 10px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-rail__list {
  display: flex;
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
  min-width: max-content;
}

.page-about .about-rail__link {
  display: block;
  padding: 9px 12px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: 0.06em;
  color: var(--c-green-deep);
  text-decoration: none;
  white-space: nowrap;
  border: 1px solid transparent;
  transition: border-color 150ms var(--ease-out), background-color 150ms var(--ease-out), color 150ms var(--ease-out);
}

.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  border-color: var(--c-orange);
  background: var(--c-orange-mist);
  color: var(--c-orange-deep);
}

.page-about .about-rail__link.is-active {
  background: var(--c-green);
  color: #fff;
  border-color: var(--c-green);
}

.page-about .about-flow {
  display: grid;
  gap: 0;
  min-width: 0;
}

/* ---------- 章节 ---------- */
.page-about .about-chapter {
  padding: 30px 0;
  border-bottom: var(--hair);
  scroll-margin-top: 84px;
}

.page-about .about-chapter--last {
  border-bottom: 0;
}

.page-about .about-chapter__head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 18px;
}

.page-about .about-chapter__index {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0.08em;
  color: var(--c-orange);
}

.page-about .about-chapter__title {
  margin: 0;
  font-size: clamp(21px, 4.4vw, 30px);
  line-height: 1.2;
  letter-spacing: -0.015em;
  font-weight: 900;
  color: var(--c-green-deep);
}

.page-about .about-chapter__grid {
  display: grid;
  gap: 22px;
}

.page-about .about-chapter__body > p {
  margin: 0 0 1.15em;
  font-size: 16px;
  line-height: 1.78;
  max-width: 40em;
}

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

/* ---------- 旁注 ---------- */
.page-about .about-aside {
  border-left: 1px solid var(--about-line);
  padding-left: 16px;
}

.page-about .about-metrics {
  display: grid;
  gap: 12px;
  margin: 0;
}

.page-about .about-metrics__row {
  border-top: var(--hair);
  padding-top: 9px;
}

.page-about .about-metrics__row:first-child {
  border-top: 1px solid var(--about-line);
}

.page-about .about-metrics__key {
  margin: 0;
  font-size: 11.5px;
  letter-spacing: 0.08em;
  color: var(--c-ink-mid);
}

.page-about .about-metrics__val {
  margin: 5px 0 0;
  font-family: var(--font-mono);
  font-size: 22px;
  line-height: 1.1;
  letter-spacing: 0.02em;
  color: var(--c-amber);
}

/* ---------- 三条要点 ---------- */
.page-about .about-points {
  display: grid;
  gap: 12px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: about-point;
}

.page-about .about-points__item {
  position: relative;
  border: var(--hair);
  border-left: 3px solid var(--c-green);
  background: #fff;
  padding: 14px 16px 15px;
  transition: border-color 180ms var(--ease-out), transform 180ms var(--ease-out);
}

.page-about .about-points__item:hover {
  border-color: var(--c-orange);
  border-left-color: var(--c-orange);
  transform: translateY(-2px);
}

.page-about .about-points__title {
  margin: 0 0 6px;
  font-size: 17px;
  font-weight: 700;
  color: var(--c-green-deep);
}

.page-about .about-points__item p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.7;
  color: var(--c-ink);
}

/* ---------- 时间轴 ---------- */
.page-about .about-timeline {
  display: grid;
  gap: 0;
  margin: 20px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-timeline__item {
  position: relative;
  padding: 0 0 24px 26px;
  border-left: 1px solid var(--about-line);
}

.page-about .about-timeline__item::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 5px;
  width: 9px;
  height: 9px;
  background: var(--c-orange);
}

.page-about .about-timeline__item:last-child {
  padding-bottom: 0;
  border-left-color: transparent;
}

.page-about .about-timeline__ver {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 20px;
  letter-spacing: 0.04em;
  color: var(--c-green);
}

.page-about .about-timeline__date {
  margin: 3px 0 10px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--c-ink-mid);
}

.page-about .about-timeline__card {
  border: var(--hair);
  background: #fff;
  padding: 14px 16px 15px;
  transition: border-color 180ms var(--ease-out), transform 180ms var(--ease-out);
}

.page-about .about-timeline__card:hover {
  border-color: var(--c-orange);
  transform: translateY(-2px);
}

.page-about .about-timeline__title {
  margin: 0 0 6px;
  font-size: 17px;
  font-weight: 700;
  color: var(--c-green-deep);
}

.page-about .about-timeline__card p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--c-ink);
}

/* ---------- 图 ---------- */
.page-about .about-figure {
  margin: 20px 0;
  border: var(--hair);
  background: #fff;
  padding: 10px;
}

.page-about .about-figure__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  background: var(--c-green-mist);
}

.page-about .about-figure__caption {
  margin: 9px 2px 2px;
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--c-ink-mid);
}

.page-about .about-figure--narrow {
  max-width: 520px;
}

/* ---------- 核验步骤 ---------- */
.page-about .about-steps {
  display: grid;
  gap: 1px;
  margin: 18px 0 22px;
  padding: 1px;
  list-style: none;
  background: rgba(38, 51, 59, 0.14);
  border: var(--hair);
}

.page-about .about-steps__item {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr);
  gap: 12px;
  align-items: start;
  background: var(--c-paper);
  padding: 14px 15px;
  transition: background-color 150ms var(--ease-out);
}

.page-about .about-steps__item:hover {
  background: var(--c-orange-mist);
}

.page-about .about-steps__num {
  font-family: var(--font-mono);
  font-size: 17px;
  letter-spacing: 0.04em;
  color: var(--c-orange);
}

.page-about .about-steps__title {
  margin: 0 0 5px;
  font-size: 16px;
  font-weight: 700;
  color: var(--c-green-deep);
}

.page-about .about-steps__text p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--c-ink);
}

/* ---------- 出口列表 ---------- */
.page-about .about-dock {
  margin-top: 30px;
  border: var(--hair);
  border-top: 3px solid var(--c-green);
  background: var(--c-green-mist);
  padding: 20px 18px 22px;
}

.page-about .about-dock__title {
  margin: 0 0 14px;
  font-size: 18px;
  font-weight: 900;
  letter-spacing: -0.01em;
  color: var(--c-green-deep);
}

.page-about .about-dock__list {
  display: grid;
  gap: 1px;
  margin: 0;
  padding: 0;
  list-style: none;
  background: rgba(30, 122, 107, 0.24);
}

.page-about .about-dock__item {
  background: var(--c-paper);
}

.page-about .about-dock__link {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 6px 16px;
  padding: 13px 15px;
  text-decoration: none;
  color: var(--c-ink);
  transition: background-color 150ms var(--ease-out), color 150ms var(--ease-out);
}

.page-about .about-dock__link:hover,
.page-about .about-dock__link:focus-visible {
  background: var(--c-orange-mist);
  color: var(--c-orange-deep);
}

.page-about .about-dock__label {
  font-size: 15.5px;
  font-weight: 700;
}

.page-about .about-dock__meta {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-ink-mid);
}

.page-about .about-dock__link:hover .about-dock__meta,
.page-about .about-dock__link:focus-visible .about-dock__meta {
  color: var(--c-orange-deep);
}

/* ---------- 中等屏 ---------- */
@media (min-width: 720px) {
  .page-about .about-masthead__inner {
    padding-bottom: 36px;
  }

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

  .page-about .about-chapter__grid {
    grid-template-columns: minmax(0, 1fr) var(--about-aside);
    gap: 30px;
    align-items: start;
  }

  .page-about .about-steps__item {
    grid-template-columns: 52px minmax(0, 1fr);
    gap: 16px;
  }

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

/* ---------- 宽屏 ---------- */
@media (min-width: 1024px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 44px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 88px;
    align-self: start;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    padding: 10px 12px;
  }

  .page-about .about-rail__list {
    flex-direction: column;
    gap: 2px;
    min-width: 0;
  }

  .page-about .about-rail__link {
    white-space: normal;
    line-height: 1.4;
  }

  .page-about .about-chapter {
    padding: 38px 0;
  }
}

/* ---------- 时间轴横向排布 ---------- */
@media (min-width: 900px) {
  .page-about .about-timeline {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    border-top: 1px solid var(--about-line);
    margin-top: 26px;
  }

  .page-about .about-timeline__item {
    border-left: 0;
    border-right: var(--hair);
    padding: 22px 24px 0 0;
  }

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

  .page-about .about-timeline__item::before {
    top: -5px;
    left: 0;
  }

  .page-about .about-timeline__card {
    min-height: 168px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-points__item,
  .page-about .about-timeline__card,
  .page-about .about-rail__link,
  .page-about .about-steps__item,
  .page-about .about-dock__link {
    transition: none;
  }

  .page-about .about-points__item:hover,
  .page-about .about-timeline__card:hover {
    transform: none;
  }
}