.page-about {
  --about-rail-w: 170px;
  --about-gap: 56px;
  position: relative;
  background: var(--ink);
  color: var(--silver);
  overflow-x: clip;
}

.page-about::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 780px;
  background:
    radial-gradient(58% 52% at 82% 4%, rgba(74, 58, 140, 0.5), transparent 72%),
    radial-gradient(44% 38% at 6% 0%, rgba(53, 224, 208, 0.12), transparent 70%);
  pointer-events: none;
  z-index: 0;
}

.page-about > * {
  position: relative;
  z-index: 1;
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding: 32px 0 40px;
}

.page-about .about-hero .breadcrumb {
  margin-bottom: 28px;
}

.page-about .about-hero__grid {
  display: grid;
  gap: 28px;
}

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

.page-about .about-hero h1 {
  margin: 14px 0 0;
  font-family: var(--font-narrow);
  font-size: clamp(30px, 6.4vw, 56px);
  font-weight: 800;
  line-height: 1.16;
  letter-spacing: 0.04em;
  color: var(--silver);
  max-width: 18ch;
}

.page-about .about-hero__deck {
  margin: 20px 0 0;
  max-width: 60ch;
  font-size: 16px;
  line-height: 1.85;
  color: rgba(232, 236, 245, 0.78);
}

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

.page-about .about-hero__index li {
  background: rgba(5, 7, 15, 0.72);
}

.page-about .about-hero__indexLink {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 13px 16px;
  font-size: 14px;
  letter-spacing: 0.03em;
  color: rgba(232, 236, 245, 0.82);
  text-decoration: none;
  transition: background var(--dur-fast) var(--ease-track), color var(--dur-fast) var(--ease-track);
}

.page-about .about-hero__indexLink .mono {
  font-size: 12px;
  color: var(--cyan);
  letter-spacing: 0.08em;
}

.page-about .about-hero__indexLink:hover,
.page-about .about-hero__indexLink:focus-visible {
  background: rgba(74, 58, 140, 0.36);
  color: #fff;
  outline: none;
}

.page-about .about-hero__media {
  margin: 36px 0 0;
}

.page-about .about-hero__media .media__img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

/* ---------- 主体骨架：左轨道 + 右叙事流 ---------- */

.page-about .about-flow {
  display: grid;
  gap: 8px;
  padding-bottom: 64px;
}

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

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

/* ---------- 章节通用 ---------- */

.page-about .about-sec {
  padding: 40px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-sec__head {
  margin-bottom: 20px;
}

.page-about .about-sec__coord {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--cyan);
}

.page-about .about-sec__title {
  margin: 0;
  font-family: var(--font-narrow);
  font-size: clamp(22px, 4.2vw, 34px);
  font-weight: 800;
  line-height: 1.3;
  letter-spacing: 0.04em;
  color: var(--silver);
}

.page-about .about-sec__lead {
  margin: 0 0 28px;
  max-width: 56ch;
  font-size: 16px;
  line-height: 1.85;
  color: rgba(232, 236, 245, 0.74);
}

.page-about .about-text {
  max-width: 68ch;
}

.page-about .about-text p {
  margin: 0 0 18px;
  font-size: 16px;
  line-height: 1.85;
  color: rgba(232, 236, 245, 0.8);
}

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

/* ---------- 四轨道分段切换 ---------- */

.page-about .about-tracks__layout {
  display: grid;
  gap: 30px;
}

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

.page-about .about-tablist {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 22px;
}

.page-about .about-tab {
  appearance: none;
  border: 1px solid var(--line);
  background: rgba(5, 7, 15, 0.6);
  color: rgba(232, 236, 245, 0.72);
  font-family: var(--font-sans);
  font-size: 13px;
  letter-spacing: 0.04em;
  padding: 10px 14px;
  cursor: pointer;
  transition:
    color var(--dur-fast) var(--ease-track),
    border-color var(--dur-fast) var(--ease-track),
    background var(--dur-fast) var(--ease-track);
}

.page-about .about-tab:hover {
  border-color: var(--line-strong);
  color: var(--silver);
}

.page-about .about-tab[aria-selected="true"] {
  background: rgba(74, 58, 140, 0.42);
  border-color: var(--cyan);
  color: #fff;
}

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

.page-about .about-panel {
  border: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(74, 58, 140, 0.16), rgba(5, 7, 15, 0.55));
  padding: 22px 20px 24px;
}

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

.page-about .about-panel__meta {
  margin: 0 0 10px;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .about-panel__title {
  margin: 0 0 12px;
  font-family: var(--font-narrow);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--silver);
}

.page-about .about-panel__body {
  margin: 0 0 16px;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(232, 236, 245, 0.78);
}

.page-about .about-panel__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 9px;
}

.page-about .about-panel__list li {
  position: relative;
  padding-left: 20px;
  font-size: 14px;
  line-height: 1.7;
  color: rgba(232, 236, 245, 0.72);
}

.page-about .about-panel__list li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 10px;
  width: 8px;
  height: 1px;
  background: var(--cyan);
}

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

.page-about .about-tracks__fig .media__img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

/* ---------- 路径一致性 ---------- */

.page-about .about-sec--split {
  display: grid;
  gap: 32px;
}

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

.page-about .about-sec__col--visual {
  display: grid;
  gap: 20px;
  justify-items: center;
}

.page-about .about-arcs {
  width: min(220px, 68%);
  height: auto;
}

.page-about .about-arcs .arc-a { stroke: var(--cyan); }
.page-about .about-arcs .arc-b { stroke: var(--nebula); }
.page-about .about-arcs .arc-c { stroke: var(--line-strong); }
.page-about .about-arcs .arc-d { stroke: var(--line); }
.page-about .about-arcs .arc-core { fill: var(--gold); }

.page-about .about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  width: 100%;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-steps__item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  background: rgba(5, 7, 15, 0.62);
  font-size: 14px;
  line-height: 1.6;
  color: rgba(232, 236, 245, 0.78);
}

.page-about .about-steps__item .mono {
  flex: 0 0 auto;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

/* ---------- 规模数据 ---------- */

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

.page-about .about-stat {
  border: 1px solid var(--line);
  background: rgba(5, 7, 15, 0.6);
  padding: 20px 16px;
}

.page-about .about-stat--lead {
  background: linear-gradient(160deg, rgba(74, 58, 140, 0.48), rgba(5, 7, 15, 0.6));
  border-color: rgba(74, 58, 140, 0.9);
}

.page-about .about-stat__num {
  margin: 0;
  font-size: clamp(26px, 6vw, 38px);
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--silver);
  line-height: 1.1;
}

.page-about .about-stat--lead .about-stat__num {
  color: var(--cyan);
}

.page-about .about-stat__label {
  margin: 10px 0 0;
  font-size: 14px;
  letter-spacing: 0.04em;
  color: rgba(232, 236, 245, 0.86);
}

.page-about .about-stat__note {
  margin: 8px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: rgba(110, 122, 155, 1);
}

/* ---------- 支持体系 ---------- */

.page-about .about-support {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-support__item {
  background: rgba(5, 7, 15, 0.55);
  padding: 20px 0;
  display: grid;
  gap: 12px;
}

.page-about .about-support__key {
  margin: 0;
  font-size: 15px;
  letter-spacing: 0.04em;
  color: var(--gold);
}

.page-about .about-support__title {
  margin: 0 0 8px;
  font-family: var(--font-narrow);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--silver);
}

.page-about .about-support__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(232, 236, 245, 0.74);
}

/* ---------- 时间线 ---------- */

.page-about .about-timeline__media {
  margin: 0 0 28px;
}

.page-about .about-timeline__media .media__img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .about-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .about-node {
  padding: 18px 0;
  border-top: 1px solid var(--line);
  transition: background var(--dur-fast) var(--ease-track);
}

.page-about .about-node__year {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--slate);
  transition: color var(--dur-fast) var(--ease-track);
}

.page-about .about-node__year::before {
  content: "";
  flex: 0 0 auto;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--slate);
  transition:
    background var(--dur-fast) var(--ease-track),
    box-shadow var(--dur-fast) var(--ease-track);
}

.page-about .about-node__title {
  margin: 10px 0 6px;
  font-family: var(--font-narrow);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--silver);
}

.page-about .about-node__note {
  margin: 0;
  max-width: 62ch;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(232, 236, 245, 0.72);
}

.page-about .about-node:hover,
.page-about .about-node:focus-within {
  background: rgba(74, 58, 140, 0.2);
}

.page-about .about-node:hover .about-node__year,
.page-about .about-node:focus-within .about-node__year {
  color: var(--cyan);
}

.page-about .about-node:hover .about-node__year::before,
.page-about .about-node:focus-within .about-node__year::before {
  background: var(--cyan);
  box-shadow: 0 0 0 4px rgba(53, 224, 208, 0.16);
}

/* ---------- 收尾入口 ---------- */

.page-about .about-start {
  margin-top: 40px;
  padding: 28px 20px 30px;
  border: 1px solid var(--line);
  background: linear-gradient(160deg, rgba(74, 58, 140, 0.34), rgba(5, 7, 15, 0.72));
}

.page-about .about-start__title {
  margin: 0 0 12px;
  font-family: var(--font-narrow);
  font-size: clamp(20px, 4vw, 28px);
  font-weight: 800;
  line-height: 1.34;
  letter-spacing: 0.04em;
  color: var(--silver);
}

.page-about .about-start__body {
  margin: 0 0 22px;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(232, 236, 245, 0.78);
}

.page-about .about-start__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.page-about .about-start__note {
  margin: 20px 0 0;
  font-size: 14px;
  line-height: 1.8;
  color: rgba(110, 122, 155, 1);
}

.page-about .about-start__note a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 224, 208, 0.4);
}

.page-about .about-start__note a:hover,
.page-about .about-start__note a:focus-visible {
  color: #fff;
  border-bottom-color: var(--cyan);
  outline: none;
}

/* ---------- 平板 ---------- */

@media (min-width: 700px) {
  .page-about .about-hero {
    padding: 48px 0 56px;
  }

  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1fr) 208px;
    align-items: start;
    gap: 40px;
  }

  .page-about .about-hero__index {
    margin-top: 6px;
  }

  .page-about .about-hero__media {
    margin-top: 48px;
  }

  .page-about .about-sec {
    padding: 56px 0;
  }

  .page-about .about-tracks__layout {
    grid-template-columns: minmax(0, 1fr) minmax(0, 320px);
    align-items: start;
  }

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

  .page-about .about-stat--lead {
    grid-column: span 2;
  }

  .page-about .about-support__item {
    grid-template-columns: 140px minmax(0, 1fr);
    align-items: baseline;
    gap: 24px;
  }

  .page-about .about-node {
    display: grid;
    grid-template-columns: 104px minmax(0, 1fr);
    gap: 28px;
    align-items: start;
  }

  .page-about .about-node__year {
    padding-top: 2px;
  }

  .page-about .about-node__title {
    margin-top: 0;
  }

  .page-about .about-start {
    padding: 36px 32px 38px;
  }
}

/* ---------- 桌面：侧边轨道常驻 ---------- */

@media (min-width: 1000px) {
  .page-about .about-flow {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: var(--about-gap);
    padding-bottom: 104px;
  }

  .page-about .about-rail {
    display: block;
    position: sticky;
    top: 40px;
    align-self: start;
    padding-top: 44px;
  }

  .page-about .about-rail__caption {
    margin: 0 0 14px;
    font-size: 11px;
    letter-spacing: 0.16em;
    color: var(--slate);
  }

  .page-about .about-rail__list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: grid;
    gap: 2px;
    border-left: 1px solid var(--line);
  }

  .page-about .about-rail__link {
    display: flex;
    align-items: baseline;
    gap: 10px;
    padding: 9px 0 9px 14px;
    font-size: 13px;
    line-height: 1.6;
    letter-spacing: 0.03em;
    color: rgba(110, 122, 155, 1);
    text-decoration: none;
    border-left: 1px solid transparent;
    margin-left: -1px;
    transition:
      color var(--dur-fast) var(--ease-track),
      border-color var(--dur-fast) var(--ease-track);
  }

  .page-about .about-rail__link .mono {
    font-size: 11px;
    letter-spacing: 0.1em;
    color: var(--slate);
    transition: color var(--dur-fast) var(--ease-track);
  }

  .page-about .about-rail__link:hover,
  .page-about .about-rail__link:focus-visible {
    color: var(--silver);
    border-left-color: var(--cyan);
    outline: none;
  }

  .page-about .about-rail__link:hover .mono,
  .page-about .about-rail__link:focus-visible .mono {
    color: var(--cyan);
  }

  .page-about .about-sec--split {
    grid-template-columns: minmax(0, 1fr) minmax(0, 300px);
    gap: 56px;
    align-items: start;
  }

  .page-about .about-sec__col--visual {
    justify-items: stretch;
  }

  .page-about .about-arcs {
    width: min(200px, 100%);
    justify-self: start;
  }
}

/* ---------- 无障碍与降级 ---------- */

@media (prefers-reduced-motion: reduce) {
  .page-about .about-hero__indexLink,
  .page-about .about-tab,
  .page-about .about-node,
  .page-about .about-node__year,
  .page-about .about-node__year::before,
  .page-about .about-rail__link,
  .page-about .about-rail__link .mono {
    transition: none;
  }
}
<<<END>>>