.page-about {
  --about-rail-w: 200px;
  --about-gap: clamp(24px, 4vw, 60px);
  --about-band: clamp(24px, 4vw, 56px);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(22px, 4vw, 40px) 0 clamp(32px, 6vw, 68px);
  border-bottom: 1px solid var(--c-line);
  background:
    radial-gradient(110% 90% at 94% -20%, rgba(34, 211, 224, .16), transparent 62%),
    radial-gradient(90% 80% at -8% 118%, rgba(255, 106, 43, .18), transparent 64%);
}

.page-about .about-hero__shear {
  position: absolute;
  top: -52px;
  right: -70px;
  width: 48%;
  height: 200px;
  background: var(--grad);
  opacity: .17;
  transform: rotate(-13deg);
  filter: blur(1px);
  pointer-events: none;
}

.page-about .crumb {
  position: relative;
  margin-bottom: clamp(18px, 3vw, 30px);
}

.page-about .about-hero__grid {
  position: relative;
  display: grid;
  gap: clamp(26px, 4vw, 46px);
}

.page-about .about-hero__eyebrow {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--c-cyan);
}

.page-about .about-hero h1 {
  margin: 0 0 16px;
  font-family: var(--font-sans);
  font-weight: 800;
  font-size: clamp(30px, 6.2vw, 52px);
  line-height: 1.18;
  letter-spacing: -.02em;
  color: var(--c-text);
}

.page-about .about-hero__lead {
  max-width: 34em;
  margin: 0 0 24px;
  font-size: clamp(16px, 1.6vw, 18px);
  color: var(--c-muted);
}

.page-about .about-hero__actions {
  gap: 10px;
}

/* 数据块 */
.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.page-about .about-stat {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 15px 16px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-sm);
  background: var(--c-panel);
  box-shadow: var(--shadow-panel);
  transition: border-color .2s var(--ease), transform .2s var(--ease);
}

.page-about .about-stat:hover,
.page-about .about-stat:focus-visible {
  border-color: var(--c-cyan);
  transform: translateY(-2px);
  outline: none;
}

.page-about .about-stat__num {
  font-family: var(--font-mono);
  font-size: clamp(24px, 3vw, 30px);
  letter-spacing: .01em;
  color: var(--c-text);
  line-height: 1.1;
}

.page-about .about-stat:nth-child(1) .about-stat__num { color: var(--c-orange); }
.page-about .about-stat:nth-child(2) .about-stat__num { color: var(--c-lime); }
.page-about .about-stat:nth-child(3) .about-stat__num { color: var(--c-cyan); }
.page-about .about-stat:nth-child(4) .about-stat__num { color: var(--c-text); }

.page-about .about-stat__label {
  font-size: 14px;
  color: var(--c-muted);
}

.page-about .about-stat__note {
  display: block;
  overflow: hidden;
  max-height: 0;
  margin-top: 0;
  opacity: 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--c-muted);
  transition: max-height .3s var(--ease), opacity .22s var(--ease), margin-top .3s var(--ease);
}

.page-about .about-stat:hover .about-stat__note,
.page-about .about-stat:focus-within .about-stat__note {
  max-height: 140px;
  margin-top: 8px;
  opacity: 1;
}

/* ---------- 双栏骨架 ---------- */
.page-about .about-layout {
  display: grid;
  gap: clamp(20px, 3vw, 34px);
  padding: var(--about-band) 0;
}

.page-about .about-rail {
  position: relative;
}

.page-about .about-rail__title {
  margin: 0 0 8px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--c-muted);
  text-transform: uppercase;
}

.page-about .about-rail .rail__list {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 2px 0 8px;
  margin: 0;
  list-style: none;
  scrollbar-width: thin;
}

.page-about .about-rail .spy-link {
  display: flex;
  align-items: center;
  gap: 9px;
  padding: 8px 10px;
  border-bottom: 2px solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .02em;
  color: var(--c-muted);
  text-decoration: none;
  white-space: nowrap;
  transition: color .2s var(--ease), border-color .2s var(--ease), background-color .2s var(--ease);
}

.page-about .about-rail .spy-link::before {
  content: "";
  flex: none;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--c-line);
  transition: background-color .2s var(--ease), box-shadow .2s var(--ease);
}

.page-about .about-rail .spy-link:hover {
  color: var(--c-text);
}

.page-about .about-rail .spy-link.is-current {
  color: var(--c-text);
  border-bottom-color: var(--c-orange);
  background: rgba(255, 106, 43, .08);
}

.page-about .about-rail .spy-link.is-current::before {
  background: var(--c-lime);
  box-shadow: 0 0 0 4px rgba(200, 255, 61, .18);
}

/* ---------- 章节 ---------- */
.page-about .about-section {
  padding: clamp(26px, 4vw, 44px) 0;
  border-top: 1px solid var(--c-line);
}

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

.page-about .about-section__no {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--c-cyan);
}

.page-about .about-section__title {
  margin: 0 0 20px;
  font-family: var(--font-sans);
  font-weight: 800;
  font-size: clamp(23px, 3.4vw, 34px);
  line-height: 1.24;
  letter-spacing: -.02em;
  color: var(--c-text);
}

.page-about .about-section .prose {
  max-width: 40em;
}

.page-about .about-hint {
  margin: 16px 0 12px;
  font-size: 14px;
  color: var(--c-muted);
}

/* 时间节点条 */
.page-about .about-nodes {
  display: grid;
  gap: 10px;
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  counter-reset: node;
}

.page-about .about-nodes__item {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 14px 16px;
  border: 1px solid var(--c-line);
  border-left: 3px solid var(--c-line);
  border-radius: var(--radius-sm);
  background: var(--c-panel);
}

.page-about .about-nodes__item:last-child {
  border-left-color: var(--c-lime);
}

.page-about .about-nodes__item:nth-child(4) {
  border-left-color: var(--c-orange);
}

.page-about .about-nodes__year {
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: .06em;
  color: var(--c-orange);
}

.page-about .about-nodes__item:nth-child(2) .about-nodes__year,
.page-about .about-nodes__item:nth-child(3) .about-nodes__year {
  color: var(--c-cyan);
}

.page-about .about-nodes__item:last-child .about-nodes__year {
  color: var(--c-lime);
}

.page-about .about-nodes__text {
  font-size: 15px;
  line-height: 1.7;
  color: var(--c-muted);
}

/* 图文并排 */
.page-about .about-split {
  display: grid;
  gap: 20px;
}

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

/* 折叠面板 */
.page-about .about-folds {
  margin-top: 18px;
}

.page-about .about-fold {
  border: 1px solid var(--c-line);
  border-radius: var(--radius-sm);
  background: var(--c-panel);
  overflow: hidden;
}

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

.page-about .about-fold > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 14px 16px;
  cursor: pointer;
  list-style: none;
  font-size: 15.5px;
  font-weight: 600;
  color: var(--c-text);
  transition: background-color .2s var(--ease);
}

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

.page-about .about-fold > summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--c-cyan);
}

.page-about .about-fold[open] > summary::after {
  content: "–";
}

.page-about .about-fold > summary:hover {
  background: rgba(34, 211, 224, .06);
}

.page-about .about-fold__body {
  padding: 14px 16px 16px;
  border-top: 1px dashed var(--c-line);
  font-size: 15px;
  line-height: 1.75;
  color: var(--c-muted);
}

/* 五类组件卡 */
.page-about .about-cards {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 6px;
  padding: 16px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-sm);
  background: var(--c-panel);
  transition: border-color .2s var(--ease), transform .2s var(--ease);
}

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

.page-about .about-card__name {
  margin: 6px 0 0;
  font-family: var(--font-sans);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -.01em;
  color: var(--c-text);
}

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

/* 大数字打断条 */
.page-about .about-break {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: 16px 20px;
  margin: clamp(8px, 2vw, 18px) 0;
  padding: clamp(18px, 3vw, 28px);
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: linear-gradient(135deg, rgba(255, 106, 43, .14) 0%, rgba(34, 211, 224, .12) 100%);
  box-shadow: var(--shadow-panel);
}

.page-about .about-break__item {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.page-about .about-break .metric {
  font-family: var(--font-mono);
  font-size: clamp(26px, 4vw, 40px);
  color: var(--c-text);
  line-height: 1.05;
}

.page-about .about-break__item:nth-child(2) .metric { color: var(--c-cyan); }
.page-about .about-break__item:nth-child(3) .metric { color: var(--c-orange); }

.page-about .about-break__label {
  font-size: 13px;
  color: var(--c-muted);
}

.page-about .about-break__note {
  grid-column: 1 / -1;
  margin: 4px 0 0;
  padding-top: 14px;
  border-top: 1px dashed rgba(147, 161, 189, .3);
  font-size: 14px;
  line-height: 1.7;
  color: var(--c-text);
}

/* 索引字段 */
.page-about .about-fields {
  display: grid;
  gap: 10px;
  margin: 20px 0;
}

.page-about .about-field {
  padding: 14px 16px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-sm);
  background: var(--c-panel);
}

.page-about .about-field__key {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--c-lime);
}

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

/* 自检清单 */
.page-about .about-checks {
  display: grid;
  gap: 12px;
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-check {
  display: flex;
  gap: 14px;
  padding: 16px;
  border: 1px solid var(--c-line);
  border-radius: var(--radius-sm);
  background: var(--c-panel);
}

.page-about .about-check__no {
  flex: none;
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: var(--c-cyan-deep);
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--c-cyan);
}

.page-about .about-check__title {
  margin: 2px 0 6px;
  font-family: var(--font-sans);
  font-size: 16.5px;
  font-weight: 700;
  color: var(--c-text);
  letter-spacing: -.01em;
}

.page-about .about-check p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--c-muted);
}

/* ---------- 结尾入口 ---------- */
.page-about .about-cta {
  border-top: 1px solid var(--c-line);
  background:
    radial-gradient(100% 140% at 12% 0%, rgba(255, 106, 43, .16), transparent 60%),
    var(--c-panel);
}

.page-about .about-cta__inner {
  display: grid;
  gap: 20px;
  padding: clamp(28px, 5vw, 56px) 0;
}

.page-about .about-cta h2 {
  margin: 0 0 8px;
  font-family: var(--font-sans);
  font-weight: 800;
  font-size: clamp(21px, 3vw, 28px);
  letter-spacing: -.02em;
  color: var(--c-text);
}

.page-about .about-cta p {
  margin: 0;
  max-width: 32em;
  font-size: 15px;
  line-height: 1.75;
  color: var(--c-muted);
}

.page-about .about-cta__actions {
  gap: 10px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about .about-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .page-about .about-nodes {
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  }

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

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr);
    align-items: start;
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 1fr) minmax(0, .8fr);
    gap: 26px;
    align-items: start;
  }

  .page-about .about-cta__inner {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    gap: 32px;
  }
}

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

  .page-about .about-rail .rail {
    position: sticky;
    top: 96px;
  }

  .page-about .about-rail .rail__list {
    flex-direction: column;
    gap: 2px;
    overflow: visible;
    padding-bottom: 0;
    border-left: 1px solid var(--c-line);
  }

  .page-about .about-rail .spy-link {
    border-bottom: 0;
    border-left: 2px solid transparent;
    margin-left: -2px;
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
    white-space: normal;
  }

  .page-about .about-rail .spy-link.is-current {
    border-left-color: var(--c-orange);
  }

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

@media (prefers-reduced-motion: reduce) {
  .page-about .about-stat,
  .page-about .about-card,
  .page-about .about-rail .spy-link,
  .page-about .about-stat__note {
    transition: none;
  }
}