.page-about {
  --about-rail-w: 200px;
  padding-bottom: var(--gap-xl);
}

/* 面包屑 */
.page-about .about-crumbs {
  max-width: var(--wrap);
  margin: 20px auto 0;
  padding: 0 20px;
}

/* 首屏 */
.page-about .about-hero {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 36px 20px 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--gap-l);
  align-items: center;
}

.page-about .about-hero-label {
  color: var(--cyan);
  margin: 0;
}

.page-about .about-hero-title {
  font-size: var(--t-display);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.04;
  color: var(--glass);
  margin: 18px 0 0;
  max-width: 16ch;
}

.page-about .about-hero-lead {
  font-size: var(--t-body);
  line-height: 1.78;
  color: var(--haze);
  max-width: 62ch;
  margin: 22px 0 0;
}

.page-about .about-hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 28px 44px;
  margin-top: 34px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

.page-about .about-hero-stat {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.page-about .about-hero-stat-value {
  font-size: 32px;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.01em;
  color: var(--orange);
}

.page-about .about-hero-stat-label {
  font-size: var(--t-sm);
  color: var(--haze);
}

.page-about .about-hero-media {
  position: relative;
  border-radius: var(--r-m);
  overflow: hidden;
  border: 1px solid var(--line);
  background: var(--deep);
}

.page-about .about-hero-media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

/* 主体骨架：移动端单列，桌面端年份轴 + 内容流 */
.page-about .about-layout {
  max-width: var(--wrap);
  margin: var(--gap-xl) auto 0;
  padding: 0 20px;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--gap-l);
}

/* 年份轴 */
.page-about .about-rail {
  position: sticky;
  top: var(--header-h);
  z-index: 6;
  margin: 0 -20px;
  padding: 10px 20px;
  background: rgba(10, 25, 48, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}

.page-about .about-rail-title {
  display: none;
}

.page-about .about-rail-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 10px;
  overflow-x: auto;
  scrollbar-width: none;
}

.page-about .about-rail-list::-webkit-scrollbar {
  display: none;
}

.page-about .about-rail-link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: var(--r-s);
  text-decoration: none;
  white-space: nowrap;
  transition: border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-rail-year {
  font-size: var(--t-sm);
  font-weight: 700;
  color: var(--haze);
}

.page-about .about-rail-label {
  font-size: var(--t-label);
  letter-spacing: 0.06em;
  color: var(--haze);
}

.page-about .about-rail-link:hover,
.page-about .about-rail-link:focus-visible {
  border-color: var(--line-strong);
  background: var(--wash);
}

.page-about .about-rail-link.is-current,
.page-about .about-rail-link[aria-current="true"] {
  border-color: var(--cyan);
  background: var(--wash);
}

.page-about .about-rail-link.is-current .about-rail-year,
.page-about .about-rail-link[aria-current="true"] .about-rail-year {
  color: var(--orange);
}

.page-about .about-rail-link:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

/* 内容流 */
.page-about .about-flow {
  display: flex;
  flex-direction: column;
  gap: var(--gap-xl);
  min-width: 0;
}

.page-about .about-chapter {
  scroll-margin-top: calc(var(--header-h) + 72px);
}

.page-about .chapter-index {
  color: var(--cyan);
  margin: 0;
}

.page-about .chapter-title {
  font-size: var(--t-h2);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.16;
  color: var(--glass);
  margin: 10px 0 0;
  max-width: 22ch;
}

.page-about .chapter-lead {
  font-size: var(--t-body);
  line-height: 1.78;
  color: var(--haze);
  margin: 14px 0 0;
  max-width: 68ch;
}

/* 左右分屏 */
.page-about .about-split {
  margin-top: var(--gap-m);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--gap-m);
  align-items: start;
}

.page-about .about-copy p {
  font-size: var(--t-body);
  line-height: 1.78;
  color: var(--glass);
  margin: 0 0 18px;
  max-width: 64ch;
}

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

.page-about .about-facts {
  border-radius: var(--r-m);
  border: 1px solid var(--line);
  padding: 24px;
}

.page-about .about-facts-title,
.page-about .about-panel-title {
  font-family: var(--font-mono);
  font-size: var(--t-label);
  letter-spacing: 0.16em;
  color: var(--cyan);
  margin: 0 0 16px;
}

.page-about .about-facts-list,
.page-about .about-partners-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.page-about .about-facts-list li,
.page-about .about-partners-list li {
  font-size: var(--t-sm);
  line-height: 1.7;
  color: var(--haze);
  padding-left: 14px;
  position: relative;
}

.page-about .about-facts-list li::before,
.page-about .about-partners-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.62em;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--orange);
}

.page-about .about-facts-list .num,
.page-about .about-partners-list .num {
  color: var(--orange);
  font-weight: 700;
}

/* 时间线 */
.page-about .about-timeline {
  margin-top: var(--gap-m);
  display: flex;
  flex-direction: column;
  gap: 0;
  border-left: 1px solid var(--line);
}

.page-about .about-milestone {
  position: relative;
  padding: 0 0 36px 24px;
  scroll-margin-top: calc(var(--header-h) + 90px);
}

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

.page-about .about-milestone::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 6px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--void);
  border: 2px solid var(--cyan);
  transition: background-color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .about-milestone:hover::before,
.page-about .about-milestone:focus-within::before {
  background: var(--orange);
  border-color: var(--orange);
}

.page-about .about-milestone-head {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 8px;
}

.page-about .about-milestone-year {
  font-size: 26px;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.01em;
  color: var(--orange);
}

.page-about .about-milestone-title {
  font-size: var(--t-h3);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--glass);
  margin: 0 0 10px;
}

.page-about .about-milestone p {
  font-size: var(--t-body);
  line-height: 1.78;
  color: var(--haze);
  margin: 0;
  max-width: 66ch;
}

/* 折线图 */
.page-about .about-chart {
  margin: var(--gap-l) 0 0;
  padding: 24px;
  border-radius: var(--r-m);
  border: 1px solid var(--line);
  background: var(--deep);
}

.page-about .about-chart-svg {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .about-chart-grid line {
  stroke: var(--line);
  stroke-width: 1;
}

.page-about .about-chart-area {
  fill: url(#aboutChartFill);
}

.page-about .about-chart-line {
  fill: none;
  stroke: var(--cyan);
  stroke-width: 2;
  stroke-linejoin: round;
  stroke-linecap: round;
}

.page-about .about-chart-dots circle {
  fill: var(--void);
  stroke: var(--orange);
  stroke-width: 2;
}

.page-about .about-chart-labels text {
  fill: var(--haze);
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
}

.page-about .about-chart figcaption {
  margin-top: 14px;
  font-size: var(--t-sm);
  line-height: 1.7;
  color: var(--haze);
}

/* 团队比例 */
.page-about .about-team-panel {
  border-radius: var(--r-m);
  padding: 24px;
}

.page-about .about-ratio {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.page-about .about-ratio-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 6px;
}

.page-about .about-ratio-name {
  font-size: var(--t-sm);
  color: var(--ink);
  font-weight: 700;
}

.page-about .about-ratio-track {
  display: block;
  height: 10px;
  border-radius: 999px;
  background: rgba(10, 25, 48, 0.10);
  overflow: hidden;
}

.page-about .about-ratio-fill {
  display: block;
  height: 100%;
  width: var(--w, 0%);
  border-radius: 999px;
}

.page-about .about-ratio-fill--cyan {
  background: linear-gradient(90deg, var(--cyan-deep), var(--cyan));
}

.page-about .about-ratio-fill--orange {
  background: linear-gradient(90deg, var(--orange-soft), var(--orange));
}

.page-about .about-ratio-val {
  font-size: var(--t-sm);
  color: var(--ink);
  font-weight: 700;
}

.page-about .about-panel-note {
  margin: 20px 0 0;
  font-size: var(--t-sm);
  line-height: 1.7;
  color: rgba(10, 25, 48, 0.72);
}

/* 数据方法步骤 */
.page-about .about-steps {
  margin-top: var(--gap-m);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.page-about .about-step {
  border: 1px solid var(--line);
  border-radius: var(--r-s);
  background: rgba(18, 41, 74, 0.55);
  padding: 0 18px;
  transition: border-color var(--dur) var(--ease);
}

.page-about .about-step:hover,
.page-about .about-step[open] {
  border-color: var(--line-strong);
}

.page-about .about-step summary {
  list-style: none;
  cursor: pointer;
  padding: 16px 0;
  display: flex;
  align-items: baseline;
  font-family: var(--font-mono);
  font-size: var(--t-sm);
  letter-spacing: 0.06em;
  font-weight: 700;
  color: var(--glass);
}

.page-about .about-step summary::-webkit-details-marker {
  display: none;
}

.page-about .about-step summary::after {
  content: "+";
  margin-left: auto;
  padding-left: 16px;
  color: var(--cyan);
  font-size: 18px;
  line-height: 1;
}

.page-about .about-step[open] summary::after {
  content: "−";
  color: var(--orange);
}

.page-about .about-step summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 2px;
}

.page-about .about-step-body {
  padding: 0 0 18px;
  font-size: var(--t-sm);
  line-height: 1.78;
  color: var(--haze);
  max-width: 68ch;
}

/* 三类内容 */
.page-about .about-pillars {
  margin-top: var(--gap-m);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--gap-s);
}

.page-about .about-pillar {
  border: 1px solid var(--line);
  border-radius: var(--r-m);
  padding: 24px;
  background: var(--deep);
  transition: transform var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .about-pillar:hover {
  transform: translateY(-3px);
  border-color: var(--line-strong);
  background: rgba(18, 41, 74, 0.9);
}

.page-about .about-pillar h3 {
  font-size: var(--t-h3);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--glass);
  margin: 14px 0 10px;
}

.page-about .about-pillar p {
  font-size: var(--t-sm);
  line-height: 1.78;
  color: var(--haze);
  margin: 0;
}

.page-about .about-capacity {
  margin: var(--gap-m) 0 0;
  padding-left: 18px;
  border-left: 3px solid var(--orange);
  font-size: var(--t-body);
  line-height: 1.78;
  color: var(--glass);
  max-width: 66ch;
}

/* 合作 */
.page-about .about-partners {
  border-radius: var(--r-m);
  border: 1px solid var(--line);
  padding: 24px;
}

/* 结尾行动 */
.page-about .about-next .chapter-head {
  margin-bottom: 0;
}

.page-about .about-actions {
  margin-top: var(--gap-m);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px 20px;
}

.page-about .about-link-soft {
  font-size: var(--t-sm);
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color var(--dur) var(--ease);
}

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

.page-about .about-link-soft:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
}

/* 页尾图 */
.page-about .about-outro {
  position: relative;
  max-width: var(--wrap);
  margin: var(--gap-xl) auto 0;
  padding: 0 20px;
  border-radius: 0;
  overflow: hidden;
}

.page-about .about-outro img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 6;
  object-fit: cover;
  border-radius: var(--r-m);
}

.page-about .about-outro-caption {
  margin-top: 14px;
  font-size: var(--t-sm);
  line-height: 1.7;
  color: var(--haze);
  max-width: 60ch;
}

.page-about .about-outro::after {
  content: "";
  display: block;
  height: 4px;
  margin-top: 28px;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--void), var(--cyan));
}

/* 桌面端 */
@media (min-width: 768px) {
  .page-about .about-hero {
    padding-top: 56px;
  }

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

  .page-about .about-ratio-row {
    grid-template-columns: 140px minmax(0, 1fr) 56px;
    align-items: center;
    gap: 12px;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--gap-l);
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--gap-l);
  }

  .page-about .about-split--reverse {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  }
}

@media (min-width: 1024px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: var(--gap-l);
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 40px);
    align-self: start;
    margin: 0;
    padding: 0;
    background: none;
    border-bottom: 0;
    backdrop-filter: none;
    z-index: 1;
  }

  .page-about .about-rail-title {
    display: block;
    font-family: var(--font-mono);
    font-size: var(--t-label);
    letter-spacing: 0.16em;
    color: var(--haze);
    margin: 0 0 16px;
  }

  .page-about .about-rail-list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    border-left: 1px solid var(--line);
  }

  .page-about .about-rail-link {
    flex-direction: column;
    align-items: flex-start;
    gap: 2px;
    white-space: normal;
    border: 0;
    border-left: 2px solid transparent;
    border-radius: 0;
    margin-left: -1px;
    padding: 12px 8px 12px 16px;
  }

  .page-about .about-rail-link:hover,
  .page-about .about-rail-link:focus-visible {
    background: var(--wash);
    border-left-color: var(--line-strong);
  }

  .page-about .about-rail-link.is-current,
  .page-about .about-rail-link[aria-current="true"] {
    background: var(--wash);
    border-left-color: var(--orange);
  }

  .page-about .about-rail-year {
    font-size: 20px;
    color: var(--glass);
  }

  .page-about .about-rail-link.is-current .about-rail-year,
  .page-about .about-rail-link[aria-current="true"] .about-rail-year {
    color: var(--orange);
  }

  .page-about .about-milestone {
    padding-left: 32px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-pillar,
  .page-about .about-rail-link,
  .page-about .about-milestone::before,
  .page-about .about-step {
    transition: none;
  }

  .page-about .about-pillar:hover {
    transform: none;
  }
}

.page-about {
  --w: 1rem;
}