.page-about {
  --ab-rail: 180px;
  --ab-gap: 48px;
  padding-bottom: 72px;
}

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

.page-about .breadcrumb {
  padding-top: 24px;
}

.page-about .fig {
  margin: 0;
}

.page-about .fig img {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  filter: saturate(.68) brightness(.86);
}

.page-about .fig__cap {
  margin-top: 10px;
}

/* 阅读进度 */
.page-about__progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--cyan), var(--gold));
  z-index: 40;
  pointer-events: none;
}

/* 首屏 */
.page-about__hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
  align-items: end;
}

.page-about__title {
  margin: 14px 0 0;
  max-width: 12em;
}

.page-about__lead {
  margin-top: 24px;
  max-width: 36em;
}

.page-about__hero-fig img {
  aspect-ratio: 10 / 7;
  object-fit: cover;
}

/* 左侧索引 + 正文 的非对称栏 */
.page-about__split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.page-about__rail {
  padding-top: 6px;
}

.page-about__body > .h2 {
  margin-top: 0;
}

.page-about__body .prose + .prose {
  margin-top: 14px;
}

/* 三项能力 */
.page-about__caps {
  margin-top: 32px;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about__cap {
  background: var(--panel);
  padding: 26px 24px 30px;
  transition: background .3s var(--ease);
}

.page-about__cap:hover {
  background: var(--panel-2);
}

.page-about__cap-num {
  margin: 0 0 14px;
  color: var(--cyan);
  letter-spacing: .18em;
}

.page-about__cap .h3 {
  margin: 0 0 10px;
}

.page-about__cap-text {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.75;
}

/* 终端覆盖 */
.page-about__terminal {
  margin-top: 40px;
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
  align-items: start;
}

.page-about__terminal .h3 {
  margin: 0 0 12px;
}

.page-about__chips {
  margin: 18px 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about__chips .tag {
  display: inline-block;
}

.page-about__terminal-fig img {
  aspect-ratio: 11 / 6.2;
  object-fit: cover;
}

/* 内容分区 */
.page-about__zones {
  margin-top: 32px;
}

.page-about__zone {
  padding: 22px 22px 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel-2);
  transition: border-color .3s var(--ease), transform .3s var(--ease);
}

.page-about__zone:hover {
  border-color: var(--cyan);
  transform: translateY(-2px);
}

.page-about__zone-num {
  margin: 0 0 12px;
  color: var(--gold);
  letter-spacing: .18em;
}

.page-about__zone .h3 {
  margin: 0 0 10px;
}

.page-about__zone-text {
  margin: 0;
  color: var(--muted);
  font-size: 15px;
  line-height: 1.75;
}

/* 节点带 */
.page-about__nodes {
  padding-top: 56px;
  padding-bottom: 56px;
}

.page-about__nodes-head {
  max-width: 48em;
}

.page-about__nodes-head .h2 {
  margin-top: 10px;
}

.page-about__regions {
  list-style: none;
  margin: 36px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about__region {
  background: var(--panel-2);
  padding: 18px 20px 20px;
  display: grid;
  grid-template-columns: auto 1fr;
  grid-template-areas:
    "code name"
    "dots note";
  column-gap: 12px;
  row-gap: 10px;
  align-items: center;
  transition: background .3s var(--ease), box-shadow .3s var(--ease);
}

.page-about__region:hover,
.page-about__region:focus-visible {
  background: var(--panel);
  box-shadow: inset 0 0 0 1px var(--cyan);
  outline: none;
}

.page-about__region-code {
  grid-area: code;
  color: var(--dim);
  letter-spacing: .14em;
}

.page-about__region-name {
  grid-area: name;
  color: var(--white);
  font-size: 16px;
  letter-spacing: .06em;
}

.page-about__region-dots {
  grid-area: dots;
  display: flex;
  gap: 5px;
}

.page-about__region-dots i {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--line);
  transition: background .3s var(--ease);
}

.page-about__region:hover .page-about__region-dots i,
.page-about__region:focus-visible .page-about__region-dots i {
  background: var(--cyan);
}

.page-about__region-note {
  grid-area: note;
  color: var(--dim);
  font-size: 12px;
  font-family: var(--font-mono);
  letter-spacing: .06em;
  transition: color .3s var(--ease);
}

.page-about__region:hover .page-about__region-note,
.page-about__region:focus-visible .page-about__region-note {
  color: var(--cyan);
}

.page-about__nodes-foot {
  margin-top: 40px;
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
  align-items: start;
}

.page-about__nodes-fig img {
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-about__nodes-note .h3 {
  margin: 0 0 12px;
}

/* 里程碑 */
.page-about__milestones {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

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

.page-about__ms-sum {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 14px;
  padding: 18px 2px;
  cursor: pointer;
  list-style: none;
}

.page-about__ms-sum::-webkit-details-marker {
  display: none;
}

.page-about__ms-ver {
  color: var(--gold);
  letter-spacing: .1em;
}

.page-about__ms-title {
  color: var(--white);
  font-size: 17px;
  line-height: 1.5;
  transition: color .25s var(--ease);
}

.page-about__ms-sum:hover .page-about__ms-title,
.page-about__ms-sum:focus-visible .page-about__ms-title {
  color: var(--cyan);
}

.page-about__ms-sum:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.page-about__ms-mark {
  width: 9px;
  height: 9px;
  border-right: 1px solid var(--muted);
  border-bottom: 1px solid var(--muted);
  transform: rotate(45deg);
  transition: transform .3s var(--ease), border-color .3s var(--ease);
}

.page-about__ms[open] .page-about__ms-mark {
  transform: rotate(-135deg);
  border-color: var(--cyan);
}

.page-about__ms-body {
  padding: 0 2px 22px;
}

.page-about__ms-body .prose {
  margin: 0;
  max-width: 44em;
}

.page-about__links {
  margin: 26px 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* 维护节奏 */
.page-about__rhythm {
  margin-top: 8px;
}

.page-about__rhythm-card {
  padding: 22px 22px 26px;
}

.page-about__rhythm-num {
  margin: 0 0 14px;
  color: var(--cyan);
  font-size: 20px;
  letter-spacing: .08em;
}

.page-about__rhythm-card .h3 {
  margin: 0 0 10px;
}

/* 结尾 CTA */
.page-about__cta {
  border-top: 1px solid var(--line);
  margin-top: 24px;
  padding-top: 48px;
}

.page-about__cta-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
  align-items: start;
}

.page-about__cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

@media (min-width: 640px) {
  .page-about__caps {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

@media (min-width: 900px) {
  .page-about {
    --ab-rail: 180px;
    --ab-gap: 48px;
  }

  .page-about__hero-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 56px;
  }

  .page-about__split {
    grid-template-columns: var(--ab-rail) minmax(0, 1fr);
    gap: var(--ab-gap);
  }

  .page-about__rail {
    position: sticky;
    top: 32px;
    align-self: start;
  }

  .page-about__terminal {
    grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
    gap: 36px;
  }

  .page-about__nodes-foot {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
    gap: 36px;
    align-items: center;
  }

  .page-about__cta-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 48px;
    align-items: end;
  }
}

@media (min-width: 1120px) {
  .page-about__regions {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about__cap,
  .page-about__zone,
  .page-about__region,
  .page-about__ms-mark,
  .page-about__ms-title {
    transition: none;
  }

  .page-about__zone:hover {
    transform: none;
  }
}