.page-about {
  --about-rail: 196px;
  padding-bottom: 56px;
}

.page-about .breadcrumbs {
  padding-top: 20px;
  font-size: 12px;
  color: var(--muted);
}

.page-about .breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 180ms var(--ease), border-color 180ms var(--ease);
}

.page-about .breadcrumbs a:hover {
  color: var(--lime);
  border-bottom-color: var(--lime);
}

.page-about .breadcrumbs span::before {
  content: "/";
  margin: 0 8px;
  color: var(--line);
}

/* 首屏 */
.page-about .about-hero {
  display: grid;
  gap: 18px;
  padding: 32px 0 28px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-kicker {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--sand);
}

.page-about .about-hero-title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(34px, 8.6vw, 88px);
  line-height: 0.95;
  letter-spacing: -0.02em;
  color: var(--ink);
  max-width: 16ch;
}

.page-about .about-lede {
  margin: 0;
  font-size: 16px;
  line-height: 1.8;
  color: var(--muted);
  max-width: 60ch;
}

.page-about .about-hero-facts {
  list-style: none;
  margin: 4px 0 0;
  padding: 16px 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  border-top: 1px solid var(--line);
}

.page-about .about-fact {
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.page-about .about-fact b {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 19px;
  font-weight: 700;
  color: var(--lime);
  line-height: 1;
}

.page-about .about-fact span {
  font-size: 12px;
  color: var(--muted);
}

/* 双栏骨架 */
.page-about .about-body {
  display: grid;
  gap: 28px;
  padding-top: 32px;
}

.page-about .about-body--tail {
  border-top: 1px solid var(--line);
  padding-top: 28px;
}

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

/* 左侧索引轨 */
.page-about .about-rail {
  min-width: 0;
}

.page-about .about-rail-title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--sand);
}

.page-about .about-rail-list {
  list-style: none;
  margin: 0 0 26px;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-rail-link {
  display: flex;
  gap: 10px;
  padding: 7px 0;
  font-size: 13px;
  line-height: 1.4;
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 180ms var(--ease), border-color 180ms var(--ease);
}

.page-about .about-rail-link span {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--sand);
  flex: none;
}

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

.page-about .about-rail-years {
  list-style: none;
  margin: 0;
  padding: 0 0 0 14px;
  display: grid;
  gap: 11px;
  border-left: 1px solid var(--line);
}

.page-about .about-rail-years li {
  position: relative;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.page-about .about-rail-years li::before {
  content: "";
  position: absolute;
  left: -18px;
  top: 7px;
  width: 6px;
  height: 1px;
  background: var(--line);
}

.page-about .about-rail-years li:last-child {
  color: var(--lime);
}

.page-about .about-rail-note {
  margin: 0;
  padding: 14px 0 0;
  border-top: 1px solid var(--line);
  font-size: 13px;
  line-height: 1.75;
  color: var(--muted);
}

/* 章节 */
.page-about .about-section {
  padding: 32px 0;
  border-top: 1px solid var(--line);
  scroll-margin-top: 84px;
}

.page-about .about-section:first-child,
.page-about .about-section--flush {
  padding-top: 0;
  border-top: 0;
}

.page-about .about-num {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--sand);
}

.page-about .about-h2 {
  margin: 0 0 18px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(25px, 5.4vw, 40px);
  line-height: 1.04;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .about-p {
  margin: 0 0 16px;
  font-size: 15px;
  line-height: 1.82;
  color: var(--muted);
  max-width: 66ch;
}

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

.page-about .about-p strong {
  color: var(--ink);
  font-weight: 600;
}

.page-about .about-pull {
  margin: 24px 0 0;
  padding: 2px 0 2px 18px;
  border-left: 3px solid var(--lime);
  font-size: 16px;
  line-height: 1.7;
  color: var(--ink);
  max-width: 58ch;
}

/* 配图 */
.page-about .about-figure {
  margin: 24px 0;
}

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

.page-about .about-figure figcaption {
  margin-top: 10px;
  font-size: 12px;
  line-height: 1.7;
  color: var(--muted);
}

.page-about .about-figure--narrow {
  max-width: 380px;
  margin-bottom: 0;
}

/* 流程 */
.page-about .flow {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
}

.page-about .flow-step {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  column-gap: 12px;
  padding: 16px 0;
  border-top: 1px solid var(--line);
}

.page-about .flow-step:last-child {
  border-bottom: 1px solid var(--line);
}

.page-about .flow-step-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  color: var(--lime);
  padding-top: 3px;
}

.page-about .flow-step-title {
  margin: 0 0 5px;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--ink);
}

.page-about .flow-step-desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--muted);
}

/* 体量数字块 */
.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 22px 0 20px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .about-stat {
  display: grid;
  align-content: start;
  gap: 6px;
  padding: 18px 15px 20px;
  background: var(--card);
  transition: background 220ms var(--ease);
}

.page-about .about-stats.is-visible .about-stat {
  background: #17362E;
}

.page-about .about-stat-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(28px, 7vw, 40px);
  font-weight: 700;
  line-height: 1;
  color: var(--lime);
  letter-spacing: -0.01em;
  transition: color 260ms var(--ease);
}

.page-about .about-stat-suffix {
  font-size: 0.55em;
  margin-left: 2px;
}

.page-about .about-stat-unit {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--sand);
}

.page-about .about-stat-label {
  font-size: 12px;
  line-height: 1.65;
  color: var(--muted);
}

/* 时间轴整段 */
.page-about .about-timeline-section {
  margin-top: 32px;
  padding: 32px 0 28px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 84px;
}

.page-about .about-banner {
  margin: 0 0 26px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

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

.page-about .about-timeline-inner {
  min-width: 0;
}

.page-about .about-track {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  position: relative;
}

.page-about .about-track::before {
  content: "";
  position: absolute;
  left: 6px;
  top: 8px;
  bottom: 14px;
  width: 1px;
  background: var(--line);
}

.page-about .about-track-item {
  position: relative;
  padding: 0 0 26px 30px;
}

.page-about .about-track-item:last-child {
  padding-bottom: 0;
}

.page-about .about-track-item::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 6px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--board);
  border: 1px solid var(--sand);
  transition: background 180ms var(--ease), border-color 180ms var(--ease), transform 180ms var(--ease);
}

.page-about .about-track-item:hover::before,
.page-about .about-track-item:focus-within::before {
  background: var(--lime);
  border-color: var(--lime);
  transform: scale(1.3);
}

.page-about .about-track-item.is-current::before {
  background: var(--lime);
  border-color: var(--lime);
}

.page-about .about-track-stamp {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--sand);
}

.page-about .about-track-title {
  margin: 5px 0 8px;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(20px, 4.6vw, 27px);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.page-about .about-track-desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.78;
  color: var(--muted);
  max-width: 56ch;
}

.page-about .about-track-more {
  margin: 8px 0 0;
  font-size: 13px;
  line-height: 1.75;
  color: var(--sand);
  opacity: 0.7;
  max-width: 56ch;
  transition: color 180ms var(--ease), opacity 180ms var(--ease);
}

.page-about .about-track-item:hover .about-track-more,
.page-about .about-track-item:focus-within .about-track-more {
  color: var(--mint);
  opacity: 1;
}

/* 标准 */
.page-about .about-principles {
  display: grid;
  gap: 22px;
  margin-top: 22px;
}

.page-about .about-principle {
  padding-left: 16px;
  border-left: 3px solid var(--lime);
}

.page-about .about-principle-title {
  margin: 0 0 7px;
  font-size: 16px;
  line-height: 1.5;
  font-weight: 600;
  color: var(--ink);
}

.page-about .about-principle-desc {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
  max-width: 58ch;
}

/* 收尾 */
.page-about .about-coda {
  margin-top: 34px;
  padding: 22px 18px;
  background: var(--board);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.page-about .about-coda-title {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--sand);
}

.page-about .about-coda .about-p {
  font-size: 14px;
  margin-bottom: 16px;
}

.page-about .about-coda-links {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .about-coda-links a {
  display: block;
  padding: 12px 14px;
  background: var(--card);
  font-size: 14px;
  color: var(--ink);
  text-decoration: none;
  transition: color 180ms var(--ease), background 180ms var(--ease);
}

.page-about .about-coda-links a::after {
  content: "→";
  margin-left: 8px;
  color: var(--sand);
  font-family: var(--font-mono);
}

.page-about .about-coda-links a:hover,
.page-about .about-coda-links a:focus-visible {
  color: var(--lime);
  background: #17362E;
}

/* 桌面端 */
@media (min-width: 900px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: 48px;
    padding-top: 40px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 32px;
    align-self: start;
    border-top: 1px solid var(--line);
    padding-top: 16px;
  }

  .page-about .about-rail--tail {
    position: static;
    border-top: 0;
    padding-top: 0;
  }

  .page-about .about-hero {
    padding: 48px 0 34px;
  }

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

  .page-about .about-principles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 36px;
  }

  .page-about .about-timeline-inner {
    max-width: 780px;
  }

  .page-about .about-section {
    padding: 40px 0;
  }
}

@media (min-width: 1180px) {
  .page-about .about-body {
    column-gap: 64px;
  }

  .page-about .about-hero-title {
    max-width: 14ch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    transition-duration: 0ms !important;
  }
}