.page-about {
  --about-measure: 38rem;
  --about-row: clamp(56px, 9vw, 112px);
  padding-bottom: var(--band);
}

/* ---------- 首屏索引头 ---------- */
.page-about .about-lede {
  padding-top: clamp(26px, 5vw, 54px);
}

.page-about .about-kicker {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.page-about .about-kicker::before {
  content: "";
  width: 34px;
  height: 1px;
  background: var(--orange);
  flex: none;
}

.page-about .about-title {
  margin: 0 0 22px;
  font-size: clamp(30px, 5.4vw, 60px);
  line-height: 1.12;
  letter-spacing: -0.02em;
  max-width: 20ch;
}

.page-about .about-lead {
  margin: 0 0 14px;
  max-width: var(--about-measure);
  font-size: 16px;
  line-height: 1.8;
  color: var(--text);
}

.page-about .about-coords {
  list-style: none;
  margin: 34px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
}

.page-about .about-coord {
  border-top: 1px solid var(--line-strong);
  padding-top: 12px;
  min-width: 0;
}

.page-about .about-coord__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.4vw, 34px);
  line-height: 1.1;
  color: var(--cyan);
  text-shadow: 0 0 16px rgba(0, 229, 255, 0.28);
}

.page-about .about-coord__label {
  display: block;
  margin-top: 6px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--muted);
}

.page-about .about-toc {
  margin: 40px 0 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-toc__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-toc__item {
  flex: none;
}

.page-about .about-toc__link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 14px 18px;
  font-size: 14px;
  color: var(--text);
  text-decoration: none;
  border-right: 1px solid var(--line);
  white-space: nowrap;
  transition: color 180ms ease, background-color 180ms ease;
}

.page-about .about-toc__link:hover,
.page-about .about-toc__link:focus-visible {
  color: var(--cyan);
  background: rgba(0, 229, 255, 0.07);
}

.page-about .about-toc__num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--cyan);
}

/* ---------- 顶部主题带 ---------- */
.page-about .about-band {
  position: relative;
  margin: clamp(40px, 6vw, 72px) 0 0;
}

.page-about .about-band::after {
  content: "";
  position: absolute;
  right: 0;
  top: -18px;
  width: 120px;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--orange));
}

.page-about .about-band img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--ink-soft);
  object-fit: cover;
}

.page-about .about-band__caption {
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--muted);
}

/* ---------- 章节骨架 ---------- */
.page-about .about-section {
  padding-top: var(--about-row);
}

.page-about .about-section__coord {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-bottom: 14px;
}

.page-about .about-num {
  font-family: var(--font-mono);
  font-size: clamp(28px, 5vw, 50px);
  line-height: 1;
  color: var(--cyan);
  text-shadow: 0 0 20px rgba(0, 229, 255, 0.3);
}

.page-about .about-tag-label {
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.page-about .about-h2 {
  margin: 0 0 18px;
  font-size: clamp(24px, 3.6vw, 36px);
  line-height: 1.25;
  letter-spacing: -0.01em;
}

.page-about .about-prose {
  max-width: var(--about-measure);
  font-size: 16px;
  line-height: 1.8;
  color: var(--text);
}

.page-about .about-prose p {
  margin: 0 0 16px;
}

.page-about .about-inline-link {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 229, 255, 0.4);
}

.page-about .about-inline-link:hover,
.page-about .about-inline-link:focus-visible {
  border-bottom-color: var(--cyan);
}

/* ---------- 01 麻烦事 ---------- */
.page-about .about-pains {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  max-width: var(--about-measure);
}

.page-about .about-pain {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 14px;
  padding: 16px 0;
  border-top: 1px dashed var(--line-strong);
}

.page-about .about-pain__num {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--orange);
  padding-top: 4px;
}

.page-about .about-pain__text {
  font-size: 16px;
  line-height: 1.75;
}

/* ---------- 02 版本路线 ---------- */
.page-about .about-timeline-bg {
  margin: 26px 0 0;
  max-width: 100%;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--line);
}

.page-about .about-timeline-bg img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  opacity: 0.75;
  object-fit: cover;
}

.page-about .about-rail {
  display: block;
  width: 100%;
  max-width: 100%;
  height: clamp(64px, 9vw, 120px);
  margin: 22px 0 0;
}

.page-about .stage-index {
  margin: 18px 0 0;
}

.page-about .stage-index__list {
  list-style: none;
  margin: 0;
  padding: 0 0 8px;
  display: flex;
  gap: 10px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .stage-index__link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  font-size: 13px;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
  transition: border-color 180ms ease, color 180ms ease;
}

.page-about .stage-index__link:hover,
.page-about .stage-index__link:focus-visible {
  border-color: var(--cyan);
  color: var(--cyan);
}

.page-about .stage-index__num {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--cyan);
}

.page-about .about-stages {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
  max-width: 46rem;
}

.page-about .about-stage {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 16px;
  padding: 20px;
  background: var(--ink-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  transition: border-color 200ms ease, transform 200ms ease, box-shadow 200ms ease;
}

.page-about .about-stage:target {
  border-color: var(--cyan);
  box-shadow: 0 0 0 1px rgba(0, 229, 255, 0.35), var(--lift);
  transform: translateY(-2px);
}

.page-about .about-stage--current {
  border-color: rgba(255, 107, 53, 0.5);
  background: linear-gradient(135deg, rgba(255, 107, 53, 0.1), var(--ink-soft) 60%);
}

.page-about .about-stage__num {
  font-family: var(--font-mono);
  font-size: 20px;
  line-height: 1.2;
  color: var(--cyan);
}

.page-about .about-stage--current .about-stage__num {
  color: var(--orange);
}

.page-about .about-stage__title {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 600;
  line-height: 1.4;
}

.page-about .about-stage__text {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--text);
}

.page-about .about-stage--current .tag {
  margin-top: 12px;
  display: inline-block;
}

/* ---------- 03 栏目分类图例 ---------- */
.page-about .about-legend {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
}

.page-about .about-legend__row {
  display: grid;
  grid-template-columns: 16px minmax(0, 1fr);
  gap: 8px 14px;
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-legend__mark {
  width: 14px;
  height: 14px;
  margin-top: 5px;
  border-radius: 3px;
  background: var(--cyan);
}

.page-about .about-legend__row--2 .about-legend__mark {
  background: var(--orange);
}

.page-about .about-legend__row--3 .about-legend__mark {
  background: var(--ok);
}

.page-about .about-legend__row--4 .about-legend__mark {
  background: var(--warn);
}

.page-about .about-legend__row--5 .about-legend__mark {
  background: var(--muted);
}

.page-about .about-legend__name {
  font-size: 16px;
  font-weight: 600;
  line-height: 1.5;
}

.page-about .about-legend__count {
  grid-column: 2;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--cyan);
  letter-spacing: 0.04em;
}

.page-about .about-legend__desc {
  grid-column: 2;
  font-size: 15px;
  line-height: 1.7;
  color: var(--text);
}

/* ---------- 04 内容运转 ---------- */
.page-about .about-ops {
  display: grid;
  gap: 24px;
  margin-top: 24px;
}

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

.page-about .panel--paper .about-ops__paper,
.page-about .about-ops__paper .prose {
  color: var(--ink);
}

.page-about .about-ops__paper .prose h3 {
  margin: 0 0 14px;
  font-size: 20px;
  line-height: 1.35;
  color: var(--ink);
}

.page-about .about-ops__paper .prose p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink);
}

.page-about .about-ops__figure {
  margin: 0;
  min-width: 0;
}

.page-about .about-ops__figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--ink-soft);
  object-fit: cover;
}

/* ---------- 05 运行规模 ---------- */
.page-about .about-figures {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.page-about .about-figure {
  background: var(--ink);
  padding: 22px 18px;
  min-width: 0;
}

.page-about .about-figure__value {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(22px, 3vw, 30px);
  line-height: 1.15;
  color: var(--cyan);
}

.page-about .about-figure__label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--muted);
}

/* ---------- 收尾路线 ---------- */
.page-about .about-route {
  margin-top: var(--about-row);
}

.page-about .about-route__list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

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

.page-about .about-route__link {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 18px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  background: linear-gradient(140deg, rgba(0, 229, 255, 0.07), transparent 62%);
  color: var(--text);
  text-decoration: none;
  transition: border-color 200ms ease, transform 200ms ease, background-color 200ms ease;
}

.page-about .about-route__link:hover,
.page-about .about-route__link:focus-visible {
  border-color: var(--cyan);
  transform: translateY(-2px);
  background-color: rgba(0, 229, 255, 0.06);
}

.page-about .about-route__name {
  font-size: 16px;
  font-weight: 600;
}

.page-about .about-route__desc {
  font-size: 13px;
  line-height: 1.6;
  color: var(--muted);
}

/* ---------- 响应式 ---------- */
@media (min-width: 760px) {
  .page-about .about-coords {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-toc__list {
    display: grid;
    grid-template-columns: repeat(5, minmax(0, 1fr));
    overflow-x: visible;
  }

  .page-about .about-toc__item:last-child .about-toc__link {
    border-right: 0;
  }

  .page-about .about-legend__row {
    grid-template-columns: 16px 150px 78px minmax(0, 1fr);
    align-items: baseline;
  }

  .page-about .about-legend__count,
  .page-about .about-legend__desc {
    grid-column: auto;
  }

  .page-about .about-figures {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

@media (min-width: 900px) {
  .page-about .about-section {
    display: grid;
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 0 40px;
    align-items: start;
  }

  .page-about .about-section__coord {
    position: sticky;
    top: 28px;
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
    margin-bottom: 0;
  }

  .page-about .about-section__coord::after {
    content: "";
    width: 1px;
    height: clamp(48px, 8vw, 96px);
    background: linear-gradient(180deg, var(--cyan), transparent);
  }

  .page-about .about-ops {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: 28px;
    align-items: start;
  }

  .page-about .about-stage {
    grid-template-columns: 56px minmax(0, 1fr);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-stage,
  .page-about .about-route__link,
  .page-about .about-toc__link {
    transition: none;
  }

  .page-about .about-stage:target,
  .page-about .about-route__link:hover,
  .page-about .about-route__link:focus-visible {
    transform: none;
  }

  .page-about .about-coord__num,
  .page-about .about-num {
    text-shadow: none;
  }
}