.page-about {
  --about-rail: 196px;
  --about-gap: clamp(28px, 4vw, 66px);
  --about-line: rgba(36, 67, 92, 0.85);
  --about-panel: rgba(20, 41, 60, 0.55);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  isolation: isolate;
  overflow: hidden;
  padding: clamp(44px, 7vw, 112px) 0 clamp(34px, 5vw, 72px);
  border-bottom: 1px solid var(--about-line);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: -42% -12% auto -12%;
  height: 150%;
  background:
    radial-gradient(48% 46% at 74% 16%, rgba(47, 240, 200, 0.11), transparent 70%),
    radial-gradient(44% 44% at 10% 72%, rgba(255, 164, 60, 0.07), transparent 72%);
  pointer-events: none;
  z-index: -1;
}

.page-about .about-hero__title {
  margin: 20px 0 0;
  max-width: 20ch;
}

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

@media (min-width: 780px) {
  .page-about .about-br {
    display: inline;
  }
}

.page-about .about-hero__lede {
  margin: clamp(18px, 2.4vw, 30px) 0 0;
  max-width: 64ch;
  color: var(--text-soft);
}

.page-about .about-hero__media {
  margin: clamp(30px, 4.4vw, 62px) 0 0;
}

/* ---------- 两栏骨架 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(30px, 4vw, 52px);
  padding-top: clamp(36px, 5vw, 72px);
}

@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: 0 var(--about-gap);
    align-items: start;
  }
}

.page-about .about-rail__inner {
  position: sticky;
  top: calc(var(--hdr-h) + 40px);
}

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

.page-about .rail-link {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-left: -1px;
  padding: 10px 0 10px 14px;
  border-left: 2px solid transparent;
  color: var(--mist);
  font-size: 13px;
  line-height: 1.4;
  text-decoration: none;
  letter-spacing: 0.02em;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.page-about .rail-link:hover,
.page-about .rail-link:focus-visible {
  color: var(--snow);
  border-left-color: var(--cyan);
  background: rgba(47, 240, 200, 0.07);
}

.page-about .rail-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

@media (max-width: 999px) {
  .page-about .about-rail__inner {
    position: static;
  }

  .page-about .rail-list {
    display: flex;
    gap: 8px;
    margin-top: 10px;
    padding: 0 0 6px;
    overflow-x: auto;
    border-left: 0;
  }

  .page-about .rail-link {
    flex: 0 0 auto;
    margin-left: 0;
    padding: 8px 13px;
    border: 1px solid var(--about-line);
    white-space: nowrap;
  }

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

/* ---------- 章节通用 ---------- */
.page-about .about-sec {
  padding: clamp(40px, 5.6vw, 88px) 0;
  border-top: 1px solid var(--about-line);
}

.page-about .about-flow > .about-sec:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .about-copy {
  max-width: 68ch;
  margin-top: clamp(20px, 2.6vw, 32px);
}

.page-about .about-copy p {
  margin: 0 0 1.15em;
  font-size: clamp(16px, 1.02vw, 17.5px);
  line-height: 1.78;
  color: var(--text-soft);
}

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

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

/* ---------- 三根主线 ---------- */
.page-about .pillar-row {
  display: grid;
  grid-template-columns: 1fr;
  margin: clamp(28px, 4vw, 52px) 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--about-line);
}

@media (min-width: 760px) {
  .page-about .pillar-row {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

.page-about .pillar {
  position: relative;
  padding: 28px 22px 30px;
  border-bottom: 1px solid var(--about-line);
  transition: background var(--dur) var(--ease);
}

@media (min-width: 760px) {
  .page-about .pillar {
    border-bottom: 0;
    border-right: 1px solid var(--about-line);
  }

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

.page-about .pillar:hover {
  background: rgba(47, 240, 200, 0.05);
}

.page-about .pillar::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 22px;
  width: 38px;
  height: 2px;
  background: var(--cyan);
  transition: width var(--dur) var(--ease);
}

.page-about .pillar:nth-child(2)::before {
  background: var(--amber);
}

.page-about .pillar:nth-child(3)::before {
  background: var(--mist);
}

.page-about .pillar:hover::before {
  width: 66px;
}

.page-about .pillar-key {
  display: block;
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 10.5px;
  letter-spacing: 0.2em;
  color: var(--cyan);
}

.page-about .pillar:nth-child(2) .pillar-key {
  color: var(--amber);
}

.page-about .pillar:nth-child(3) .pillar-key {
  color: var(--mist);
}

.page-about .pillar-title {
  margin: 0 0 10px;
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--snow);
}

.page-about .pillar-text {
  margin: 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--mist);
}

/* ---------- 发展节点带 ---------- */
.page-about .about-timeline__note {
  margin: 18px 0 0;
  font-size: 13.5px;
  letter-spacing: 0.02em;
  color: var(--mist);
}

.page-about .tl-strip {
  display: grid;
  grid-auto-flow: column;
  grid-auto-columns: minmax(228px, 252px);
  margin: clamp(26px, 3.6vw, 44px) 0 0;
  padding: 0 0 8px;
  list-style: none;
  overflow-x: auto;
  border-top: 1px solid var(--about-line);
  scroll-snap-type: x proximity;
}

.page-about .tl-strip:focus-visible {
  outline: 1px solid var(--amber);
  outline-offset: 4px;
}

.page-about .tl-node {
  position: relative;
  padding: 30px 22px 34px;
  border-right: 1px solid var(--about-line);
  scroll-snap-align: start;
  transition: background var(--dur) var(--ease);
}

.page-about .tl-node:last-child {
  border-right: 0;
}

.page-about .tl-node::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 40px;
  height: 2px;
  background: var(--cyan);
  opacity: 0.45;
  transition: width 220ms var(--ease), opacity var(--dur) var(--ease);
}

.page-about .tl-node:hover,
.page-about .tl-node:focus-visible {
  background: rgba(47, 240, 200, 0.055);
}

.page-about .tl-node:hover::before,
.page-about .tl-node:focus-visible::before {
  width: 100%;
  opacity: 1;
}

.page-about .tl-seq {
  display: block;
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--cyan);
}

.page-about .tl-title {
  margin: 0 0 10px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.4;
  color: var(--snow);
  transition: color var(--dur) var(--ease);
}

.page-about .tl-node:hover .tl-title {
  color: var(--cyan);
}

.page-about .tl-note {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--mist);
}

.page-about .tl-figure {
  margin: clamp(26px, 3.6vw, 44px) 0 0;
}

/* ---------- 团队技能树 ---------- */
.page-about .tree-root {
  display: inline-flex;
  align-items: baseline;
  gap: 12px;
  margin: clamp(26px, 3.4vw, 44px) 0 14px;
  padding: 14px 24px;
  background: var(--ink-step);
  border-left: 2px solid var(--cyan);
}

.page-about .tree-root__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 26px;
  letter-spacing: -0.02em;
  color: var(--cyan);
}

.page-about .tree-root__label {
  font-size: 14px;
  letter-spacing: 0.08em;
  color: var(--text-soft);
}

.page-about .tree-branches {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 2px;
}

.page-about .tree-branches::before {
  content: "";
  position: absolute;
  left: 17px;
  top: 0;
  bottom: 0;
  width: 1px;
  background: linear-gradient(to bottom, var(--cyan), rgba(47, 240, 200, 0.1));
}

.page-about .tree-branch {
  position: relative;
  padding: 20px 20px 20px 54px;
  background: var(--about-panel);
  transition: background var(--dur) var(--ease);
}

.page-about .tree-branch::before {
  content: "";
  position: absolute;
  left: 17px;
  top: 0;
  bottom: 0;
  width: 22px;
  border-top: 1px solid var(--about-line);
  border-bottom: 1px solid var(--about-line);
  border-right: 1px solid var(--about-line);
  border-radius: 0 8px 8px 0;
  opacity: 0.9;
  transition: border-color var(--dur) var(--ease);
}

.page-about .tree-branch::after {
  content: "";
  position: absolute;
  left: 14px;
  top: 50%;
  width: 7px;
  height: 7px;
  margin-top: -3.5px;
  background: var(--cyan);
  border-radius: 50%;
  transition: background var(--dur) var(--ease), box-shadow var(--dur) var(--ease);
}

.page-about .tree-branch:hover {
  background: rgba(20, 41, 60, 0.85);
}

.page-about .tree-branch:hover::before {
  border-color: rgba(47, 240, 200, 0.45);
}

.page-about .tree-branch:hover::after {
  background: var(--amber);
  box-shadow: 0 0 0 4px rgba(255, 164, 60, 0.18);
}

.page-about .tree-node {
  display: inline-flex;
  align-items: baseline;
  gap: 10px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--snow);
}

.page-about .tree-node__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .tree-note {
  margin: 9px 0 0;
  max-width: 62ch;
  font-size: 14.5px;
  line-height: 1.72;
  color: var(--mist);
}

/* ---------- 内容方法 ---------- */
.page-about .method-list {
  list-style: none;
  margin: clamp(28px, 3.8vw, 48px) 0 0;
  padding: 0;
}

.page-about .method-step {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 20px;
  padding-bottom: clamp(28px, 3.4vw, 46px);
}

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

.page-about .method-step:not(:last-child)::after {
  content: "";
  position: absolute;
  left: 22px;
  top: 56px;
  bottom: 14px;
  width: 1px;
  background: var(--about-line);
}

.page-about .method-num {
  display: grid;
  place-items: center;
  width: 45px;
  height: 45px;
  background: var(--ink-step);
  border: 1px solid var(--about-line);
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 14px;
  color: var(--cyan);
  transition: border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.page-about .method-step:hover .method-num {
  border-color: var(--cyan);
  background: rgba(47, 240, 200, 0.12);
}

.page-about .method-title {
  margin: 8px 0 12px;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--snow);
}

.page-about .method-text {
  margin: 0;
  max-width: 66ch;
  font-size: 15.5px;
  line-height: 1.78;
  color: var(--text-soft);
}

/* ---------- 社区共建 ---------- */
.page-about .community-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(26px, 3.6vw, 48px);
  margin-top: clamp(24px, 3.2vw, 40px);
  align-items: start;
}

@media (min-width: 900px) {
  .page-about .community-grid {
    grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.72fr);
  }
}

.page-about .community-grid .about-copy {
  margin-top: 0;
}

.page-about .community-figure {
  margin: 0;
}

.page-about .about-stats {
  margin-top: clamp(30px, 4vw, 52px);
}

.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 18px 26px;
  margin-top: clamp(28px, 3.6vw, 46px);
  padding: clamp(20px, 2.6vw, 30px) clamp(20px, 2.6vw, 32px);
  background: linear-gradient(100deg, rgba(255, 164, 60, 0.1), rgba(47, 240, 200, 0.06) 70%, transparent);
  border-left: 2px solid var(--amber);
}

.page-about .about-cta__text {
  margin: 0;
  flex: 1 1 260px;
  font-size: 15.5px;
  line-height: 1.65;
  color: var(--text-soft);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

@media (max-width: 520px) {
  .page-about .pillar,
  .page-about .tree-branch,
  .page-about .tl-node {
    padding-left: 18px;
    padding-right: 16px;
  }

  .page-about .tree-branch {
    padding-left: 46px;
  }

  .page-about .pillar::before {
    left: 18px;
  }

  .page-about .method-step {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .page-about .method-step:not(:last-child)::after {
    display: none;
  }
}
<<<END>>>