.page-about {
  background: var(--c-bg);
  color: var(--c-text);
  font-family: var(--f-body);
  line-height: 1.75;
  padding-bottom: clamp(40px, 6vw, 80px);
}

/* ---------- 顶部与面包屑 ---------- */
.page-about .about-top {
  padding-top: clamp(14px, 2vw, 22px);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(24px, 4vw, 52px) 0 clamp(30px, 4vw, 56px);
}

.page-about .about-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.5vw, 48px);
}

.page-about .about-hero-copy .index-label {
  display: inline-block;
  margin-bottom: 14px;
}

.page-about .about-hero-copy h1 {
  font-family: var(--f-display);
  font-weight: 900;
  font-size: clamp(30px, 5.6vw, 56px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  margin: 0 0 18px;
  max-width: 18em;
}

.page-about .about-lede {
  margin: 0;
  font-size: clamp(15px, 1.1vw, 17px);
  line-height: 1.8;
  max-width: 42em;
}

.page-about .hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--c-line);
  border: 1px solid var(--c-line);
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 0;
}

.page-about .hero-stat {
  background: var(--c-bg);
  padding: 14px 16px 15px;
}

.page-about .hero-stat dt {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--c-muted);
  margin-bottom: 8px;
}

.page-about .hero-stat dd {
  margin: 0;
  font-family: var(--f-mono);
  font-size: clamp(24px, 3.2vw, 32px);
  font-weight: 700;
  line-height: 1;
  color: var(--c-cyan);
  letter-spacing: -0.01em;
}

.page-about .hero-stat dd span {
  font-family: var(--f-body);
  font-size: 12px;
  font-weight: 400;
  color: var(--c-muted);
  margin-left: 4px;
}

.page-about .hero-stat:nth-child(3) dd {
  color: var(--c-text);
}

.page-about .hero-stat:nth-child(4) dd {
  color: var(--c-orange);
}

.page-about .about-hero-media {
  margin: 0;
}

.page-about .about-hero-media .media-cap {
  margin-top: 10px;
}

/* ---------- 主体双栏 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.5vw, 48px);
  padding-top: clamp(28px, 4vw, 50px);
}

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

.page-about .about-rail {
  display: grid;
  gap: 16px;
  min-width: 0;
}

.page-about .rail-block {
  border: 1px solid var(--c-line);
  border-radius: var(--radius);
  background: var(--c-bg-deep);
  padding: 16px 16px 14px;
}

.page-about .rail-title {
  margin: 0 0 12px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--c-cyan-deep);
}

.page-about .rail-item {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 9px 0;
  border-bottom: 1px dashed var(--c-line);
  color: var(--c-text);
  text-decoration: none;
  transition: color 0.16s ease;
}

.page-about .rail-item:last-child {
  border-bottom: 0;
  padding-bottom: 2px;
}

.page-about .rail-v {
  font-family: var(--f-mono);
  font-size: 13px;
  font-weight: 700;
  color: var(--c-cyan);
  min-width: 44px;
}

.page-about .rail-y {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--c-muted);
  margin-left: auto;
}

.page-about .rail-item:hover,
.page-about .rail-item:focus-visible {
  color: var(--c-orange);
}

.page-about .rail-item:hover .rail-v,
.page-about .rail-item:focus-visible .rail-v {
  color: var(--c-orange);
}

.page-about .rail-stat {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 10px;
  padding: 8px 0;
  border-bottom: 1px solid var(--c-line);
  font-size: 13.5px;
  color: var(--c-muted);
}

.page-about .rail-stat:last-child {
  border-bottom: 0;
  padding-bottom: 2px;
}

.page-about .rail-stat b {
  font-family: var(--f-mono);
  font-size: 15px;
  font-weight: 700;
  color: var(--c-text);
}

/* ---------- 通用区块 ---------- */
.page-about .about-sec {
  border-top: 1px solid var(--c-line);
  padding: clamp(28px, 4vw, 48px) 0;
  scroll-margin-top: calc(var(--header-h) + 16px);
}

.page-about .ab-head {
  margin-bottom: clamp(18px, 2.4vw, 28px);
}

.page-about .ab-title {
  font-family: var(--f-display);
  font-weight: 800;
  font-size: clamp(22px, 3vw, 32px);
  line-height: 1.22;
  letter-spacing: -0.01em;
  margin: 10px 0 8px;
}

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

.page-about .ab-p {
  margin: 0 0 16px;
  font-size: 15.5px;
  line-height: 1.85;
}

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

.page-about .ab-figure {
  margin: 0 0 clamp(20px, 2.6vw, 28px);
}

.page-about .ab-figure .media-cap {
  margin-top: 10px;
}

/* ---------- 速览清单 ---------- */
.page-about .take-list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .take-item {
  background: var(--c-bg);
  padding: 14px 16px 15px;
  display: grid;
  gap: 7px;
}

.page-about .take-when {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--c-orange);
}

.page-about .take-text {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--c-muted);
}

.page-about .take-text strong {
  color: var(--c-text);
  font-weight: 600;
}

/* ---------- 栏目索引 ---------- */
.page-about .ab-channels {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--c-line);
}

.page-about .ab-channel {
  border-bottom: 1px solid var(--c-line);
}

.page-about .ab-channel-link {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr) 18px;
  grid-template-rows: auto auto;
  gap: 4px 12px;
  padding: 16px 10px 16px 0;
  border-left: 2px solid transparent;
  color: inherit;
  text-decoration: none;
  transition: background-color 0.16s ease, border-color 0.16s ease;
}

.page-about .ab-channel-idx {
  grid-column: 1;
  grid-row: 1 / span 2;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--c-muted);
  padding-top: 3px;
}

.page-about .ab-channel-name {
  grid-column: 2;
  grid-row: 1;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.4;
}

.page-about .ab-channel-desc {
  grid-column: 2;
  grid-row: 2;
  font-size: 14px;
  line-height: 1.7;
  color: var(--c-muted);
}

.page-about .ab-channel-go {
  grid-column: 3;
  grid-row: 1 / span 2;
  align-self: center;
  font-family: var(--f-mono);
  font-size: 15px;
  color: var(--c-cyan-deep);
}

.page-about .ab-channel-link:hover,
.page-about .ab-channel-link:focus-visible {
  background: rgba(43, 232, 200, 0.05);
  border-left-color: var(--c-cyan);
}

.page-about .ab-channel-link:hover .ab-channel-name,
.page-about .ab-channel-link:focus-visible .ab-channel-name {
  color: var(--c-cyan);
}

.page-about .ab-channel-link.is-current {
  background: rgba(43, 232, 200, 0.04);
  border-left-color: var(--c-cyan-deep);
}

.page-about .ab-channel-link.is-current .ab-channel-name {
  color: var(--c-cyan);
}

/* ---------- 团队三栏 ---------- */
.page-about .ab-team {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .ab-team-col {
  background: var(--c-bg);
  padding: 20px 18px 22px;
  transition: background-color 0.16s ease;
}

.page-about .ab-team-col:hover {
  background: rgba(110, 91, 255, 0.07);
}

.page-about .ab-team-num {
  display: block;
  font-family: var(--f-mono);
  font-size: 30px;
  font-weight: 700;
  line-height: 1;
  color: var(--c-cyan);
  letter-spacing: -0.02em;
}

.page-about .ab-team-role {
  margin: 12px 0 9px;
  font-size: 16px;
  font-weight: 600;
}

.page-about .ab-team-desc {
  margin: 0 0 14px;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--c-muted);
}

.page-about .ab-team-flow {
  margin: 0;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--c-orange);
}

/* ---------- 版本时间线 ---------- */
.page-about .about-wide {
  min-width: 0;
}

.page-about .vtl {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  border-top: 1px solid var(--c-line);
  -webkit-overflow-scrolling: touch;
}

.page-about .vtl-node {
  position: relative;
  flex: 0 0 min(78vw, 268px);
  scroll-snap-align: start;
  padding: 24px 18px 26px;
  border-right: 1px solid var(--c-line);
  border-bottom: 1px solid var(--c-line);
  transition: background-color 0.16s ease;
}

.page-about .vtl-node::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 32px;
  height: 2px;
  background: var(--c-cyan-deep);
  transition: width 0.2s ease, background-color 0.2s ease;
}

.page-about .vtl-node:hover {
  background: rgba(43, 232, 200, 0.045);
}

.page-about .vtl-node:hover::before {
  width: 100%;
  background: var(--c-cyan);
}

.page-about .vtl-ver {
  display: block;
  font-family: var(--f-mono);
  font-size: 21px;
  font-weight: 700;
  line-height: 1;
  color: var(--c-cyan);
}

.page-about .vtl-year {
  display: block;
  margin: 6px 0 14px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--c-muted);
}

.page-about .vtl-title {
  margin: 0 0 10px;
  font-size: 15px;
  font-weight: 600;
  line-height: 1.5;
}

.page-about .vtl-points {
  margin: 0;
  padding-left: 16px;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--c-muted);
}

.page-about .vtl-points li {
  margin-bottom: 5px;
}

.page-about .vtl-points li:last-child {
  margin-bottom: 0;
}

.page-about .ab-figure-wide {
  margin-top: clamp(22px, 3vw, 32px);
}

/* ---------- 数据流程 ---------- */
.page-about .ab-flow {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  padding-bottom: 6px;
}

.page-about .flow-svg {
  display: block;
  width: 100%;
  min-width: 620px;
  height: auto;
}

.page-about .flow-svg .fs-rule {
  stroke: var(--c-line);
  stroke-width: 1;
}

.page-about .flow-svg .fs-box {
  fill: none;
  stroke: var(--c-line);
  stroke-width: 1;
}

.page-about .flow-svg .fs-num {
  fill: var(--c-cyan-deep);
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
}

.page-about .flow-svg .fs-t {
  fill: var(--c-text);
  font-family: var(--f-body);
  font-size: 15px;
  font-weight: 600;
}

.page-about .flow-svg .fs-s {
  fill: var(--c-muted);
  font-family: var(--f-body);
  font-size: 12px;
}

.page-about .flow-svg .fs-arrow {
  fill: none;
  stroke: var(--c-cyan-deep);
  stroke-width: 1.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.page-about .ab-metrics {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .ab-metrics > li {
  background: var(--c-bg);
  padding: 14px 16px 16px;
}

.page-about .ab-metric-v {
  display: block;
  font-family: var(--f-mono);
  font-size: 22px;
  font-weight: 700;
  line-height: 1.1;
  color: var(--c-text);
}

.page-about .ab-metric-v em {
  font-style: normal;
  font-size: 12px;
  font-weight: 400;
  color: var(--c-muted);
  margin-left: 3px;
}

.page-about .ab-metric-k {
  display: block;
  margin-top: 7px;
  font-size: 13px;
  color: var(--c-muted);
}

/* ---------- 服务对象 ---------- */
.page-about .ab-aud {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(14px, 2vw, 20px);
}

.page-about .ab-aud-item {
  border: 1px solid var(--c-line);
  border-top: 2px solid var(--c-cyan-deep);
  border-radius: var(--radius);
  background: var(--c-bg-deep);
  padding: 18px 16px 18px;
  transition: transform 0.16s ease, border-color 0.16s ease;
}

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

.page-about .ab-tag {
  display: inline-block;
  font-family: var(--f-mono);
  font-size: 10.5px;
  letter-spacing: 0.1em;
  color: var(--c-orange);
  border: 1px solid var(--c-amber);
  border-radius: 2px;
  padding: 3px 7px;
}

.page-about .ab-aud-title {
  margin: 14px 0 10px;
  font-size: 17px;
  font-weight: 600;
  line-height: 1.45;
}

.page-about .ab-aud-text {
  margin: 0 0 14px;
  font-size: 14.5px;
  line-height: 1.8;
  color: var(--c-muted);
}

.page-about .ab-aud-route {
  margin: 0;
  font-size: 13px;
  color: var(--c-muted);
}

.page-about .ab-aud-route a {
  color: var(--c-cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--c-cyan-deep);
  transition: color 0.16s ease, border-color 0.16s ease;
}

.page-about .ab-aud-route a:hover,
.page-about .ab-aud-route a:focus-visible {
  color: var(--c-orange);
  border-color: var(--c-amber);
}

/* ---------- 收尾 ---------- */
.page-about .ab-cta .ab-title {
  margin-top: 0;
}

.page-about .ab-cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 22px;
}

/* ---------- 桌面端 ---------- */
@media (min-width: 640px) {
  .page-about .hero-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

@media (min-width: 860px) {
  .page-about .about-hero-grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
  }

  .page-about .ab-team {
    grid-template-columns: 1.15fr 1fr 0.95fr;
  }

  .page-about .vtl {
    overflow: visible;
    scroll-snap-type: none;
  }

  .page-about .vtl-node {
    flex: 1 1 0;
    min-width: 0;
  }
}

@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: minmax(0, 7fr) minmax(0, 3fr);
    gap: clamp(32px, 4vw, 64px);
    align-items: start;
  }

  .page-about .about-main {
    grid-column: 1;
    grid-row: 1;
  }

  .page-about .about-rail {
    grid-column: 2;
    grid-row: 1;
    position: sticky;
    top: calc(var(--header-h) + 22px);
    align-self: start;
  }

  .page-about .about-wide {
    grid-column: 1 / -1;
  }
}

/* ---------- 窄屏兜底 ---------- */
@media (max-width: 480px) {
  .page-about .ab-channel-link {
    grid-template-columns: 32px minmax(0, 1fr) 14px;
    gap: 4px 10px;
  }

  .page-about .ab-team-num {
    font-size: 26px;
  }
}