.page-about {
  --ab-rail: 176px;
  --ab-ink: var(--c-anno);
}

/* ---------- 首屏框景 ---------- */
.page-about .ab-hero {
  padding-top: 28px;
}

.page-about .ab-hero__frame {
  position: relative;
  margin-top: 18px;
  padding: 40px 22px 34px;
  border: 1px solid var(--c-line);
  background:
    radial-gradient(140% 110% at 92% -12%, rgba(138, 123, 255, .20), transparent 58%),
    linear-gradient(180deg, rgba(60, 242, 210, .07), rgba(60, 242, 210, 0) 44%),
    var(--c-panel-2);
  overflow: hidden;
}

.page-about .ab-hero__frame::before,
.page-about .ab-hero__frame::after {
  content: "";
  position: absolute;
  width: 22px;
  height: 22px;
  border: 2px solid var(--c-cyan);
  opacity: .8;
  pointer-events: none;
}

.page-about .ab-hero__frame::before {
  top: 10px;
  left: 10px;
  border-right: 0;
  border-bottom: 0;
}

.page-about .ab-hero__frame::after {
  right: 10px;
  bottom: 10px;
  border-left: 0;
  border-top: 0;
}

.page-about .ab-hero__side {
  display: none;
}

.page-about .ab-hero__tag {
  margin: 0;
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--c-cyan);
}

.page-about .ab-hero__title {
  margin: 14px 0 0;
  font-size: clamp(32px, 5.4vw, 72px);
  line-height: 1;
  letter-spacing: -.01em;
  font-weight: 800;
  color: var(--c-white);
  max-width: 15em;
}

.page-about .ab-hero__lede {
  margin: 20px 0 0;
  max-width: 40em;
  font-size: 17px;
  line-height: 1.75;
  color: var(--c-mute);
}

.page-about .ab-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 30px 0 0;
  padding: 0;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .ab-hero__facts > div {
  background: var(--c-panel);
  padding: 14px 14px 16px;
}

.page-about .ab-hero__facts dt {
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--c-anno);
}

.page-about .ab-hero__facts dd {
  margin: 10px 0 0;
  line-height: 1;
}

.page-about .ab-num {
  font-family: var(--font-mono);
  font-size: clamp(26px, 4.6vw, 40px);
  letter-spacing: -.02em;
  color: var(--c-white);
}

.page-about .ab-unit {
  margin-left: 4px;
  font-size: 12px;
  color: var(--c-anno);
}

.page-about .ab-hero__band {
  margin: 36px 0 0;
  border-top: 1px solid var(--c-line);
  border-bottom: 1px solid var(--c-line);
}

.page-about .ab-hero__band img {
  display: block;
  width: 100%;
  height: auto;
  max-height: 60vh;
  object-fit: cover;
}

/* ---------- 轨道 + 长文画布 ---------- */
.page-about .ab-shell {
  margin-top: 44px;
}

.page-about .ab-rail {
  margin-bottom: 30px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--c-line);
}

.page-about .ab-rail__cap {
  margin: 0 0 10px;
  font-size: 11px;
  letter-spacing: .22em;
  color: var(--c-dim);
}

.page-about .ab-rail__list {
  display: flex;
  gap: 8px;
  margin: 0;
  padding: 0 0 4px;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .ab-rail__node {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 11px;
  border: 1px solid var(--c-line);
  color: var(--c-mute);
  font-size: 13px;
  text-decoration: none;
  white-space: nowrap;
  transition: color .2s var(--ease), border-color .2s var(--ease);
}

.page-about .ab-rail__num {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--c-cyan);
}

.page-about .ab-rail__node:hover,
.page-about .ab-rail__node:focus-visible {
  color: var(--c-white);
  border-color: var(--c-cyan);
}

/* ---------- 章节 ---------- */
.page-about .ab-stage {
  padding: 34px 0 42px;
  border-top: 1px solid var(--c-line);
}

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

.page-about .ab-stage__head {
  display: grid;
  grid-template-columns: 26px minmax(0, 1fr);
  gap: 10px;
  align-items: start;
}

.page-about .ab-stage__no {
  writing-mode: vertical-rl;
  font-family: var(--font-mono);
  color: var(--c-cyan);
  letter-spacing: .22em;
  padding-top: 4px;
}

.page-about .ab-stage__title {
  margin: 0;
  font-size: clamp(23px, 3.2vw, 38px);
  line-height: 1.12;
  font-weight: 800;
  color: var(--c-white);
  letter-spacing: -.01em;
}

.page-about .ab-stage__sub {
  margin: 10px 0 0;
  font-size: 14px;
  line-height: 1.6;
  color: var(--c-anno);
}

.page-about .ab-stage__body {
  margin-top: 20px;
}

.page-about .ab-stage__body p {
  margin: 0 0 16px;
  max-width: 40em;
  font-size: 17px;
  line-height: 1.75;
  color: var(--c-mute);
}

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

.page-about .ab-note {
  margin-top: 22px;
  padding-left: 14px;
  border-left: 2px solid var(--c-line);
  font-size: 15px;
  color: var(--c-anno);
}

.page-about .ab-points {
  display: grid;
  gap: 12px;
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
  max-width: 42em;
}

.page-about .ab-points li {
  position: relative;
  padding-left: 22px;
  font-size: 16px;
  line-height: 1.7;
  color: var(--c-mute);
}

.page-about .ab-points li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: 8px;
  height: 8px;
  border: 1px solid var(--c-cyan);
}

/* 四道工序 */
.page-about .ab-steps {
  counter-reset: abstep;
  display: grid;
  gap: 1px;
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .ab-steps li {
  background: var(--c-panel-2);
  padding: 18px 18px 18px 20px;
}

.page-about .ab-steps li::before {
  counter-increment: abstep;
  content: counter(abstep, decimal-leading-zero);
  display: block;
  margin-bottom: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--c-amber);
}

.page-about .ab-steps h3 {
  margin: 0;
  font-size: 16px;
  color: var(--c-white);
  font-weight: 700;
}

.page-about .ab-steps p {
  margin: 8px 0 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--c-mute);
}

/* 团队 */
.page-about .ab-team {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 22px 0 0;
  background: var(--c-line);
  border: 1px solid var(--c-line);
}

.page-about .ab-team > div {
  background: var(--c-panel);
  padding: 16px 15px 18px;
}

.page-about .ab-team .k {
  margin: 0;
  font-size: 13px;
  color: var(--c-mute);
}

.page-about .ab-team .v {
  margin: 8px 0 0;
  font-family: var(--font-mono);
  font-size: 26px;
  line-height: 1.1;
  color: var(--c-white);
}

/* 版本演进 */
.page-about .ab-versions {
  margin: 24px 0 22px;
  padding: 0 0 0 20px;
  list-style: none;
  border-left: 1px solid var(--c-line);
}

.page-about .ab-versions li {
  position: relative;
  padding: 0 0 20px 12px;
}

.page-about .ab-versions li:last-child {
  padding-bottom: 0;
}

.page-about .ab-versions li::before {
  content: "";
  position: absolute;
  left: -25px;
  top: 5px;
  width: 9px;
  height: 9px;
  background: var(--c-panel-2);
  border: 2px solid var(--c-cyan);
  border-radius: 50%;
}

.page-about .ab-versions strong {
  display: block;
  margin-bottom: 5px;
  font-size: 16px;
  color: var(--c-white);
}

.page-about .ab-versions span {
  font-size: 15px;
  line-height: 1.7;
  color: var(--c-mute);
}

/* 图片 */
.page-about .ab-figure {
  margin: 26px 0 0;
}

.page-about .ab-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--c-line);
}

.page-about .ab-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--c-dim);
}

/* 章节内链 */
.page-about .link-more {
  color: var(--c-cyan);
}

.page-about .ab-stage__body .link-more:hover {
  color: var(--c-amber);
}

/* ---------- 结尾行动 ---------- */
.page-about .ab-cta {
  margin-top: 20px;
}

.page-about .ab-cta__box {
  padding: 34px 22px 30px;
  border: 1px solid var(--c-line);
  background:
    linear-gradient(115deg, rgba(60, 242, 210, .10), transparent 52%),
    linear-gradient(255deg, rgba(255, 162, 58, .10), transparent 46%),
    var(--c-panel-2);
}

.page-about .ab-cta__k {
  margin: 0;
  font-size: 12px;
  letter-spacing: .22em;
  color: var(--c-amber);
}

.page-about .ab-cta__title {
  margin: 14px 0 0;
  font-size: clamp(22px, 3.4vw, 34px);
  line-height: 1.2;
  font-weight: 800;
  color: var(--c-white);
  max-width: 22em;
}

.page-about .ab-cta__text {
  margin: 14px 0 0;
  max-width: 38em;
  font-size: 16px;
  line-height: 1.75;
  color: var(--c-mute);
}

.page-about .ab-cta__acts {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 24px 0 0;
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 768px) {
  .page-about .ab-hero {
    padding-top: 40px;
  }

  .page-about .ab-hero__frame {
    padding: 52px 40px 44px;
  }

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

  .page-about .ab-hero__facts > div {
    padding: 18px 18px 20px;
  }

  .page-about .ab-stage {
    padding: 42px 0 54px;
  }

  .page-about .ab-stage__head {
    grid-template-columns: 34px minmax(0, 1fr);
    gap: 16px;
  }

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

  .page-about .ab-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .ab-cta__box {
    padding: 44px 40px 40px;
  }
}

/* ---------- 桌面：轨道常驻 ---------- */
@media (min-width: 1080px) {
  .page-about .ab-hero__frame {
    padding: 64px 56px 52px;
  }

  .page-about .ab-hero__side {
    display: block;
    position: absolute;
    top: 56px;
    right: 26px;
    writing-mode: vertical-rl;
    color: var(--c-dim);
    letter-spacing: .24em;
  }

  .page-about .ab-shell {
    display: grid;
    grid-template-columns: var(--ab-rail) minmax(0, 1fr);
    gap: 48px;
    align-items: start;
    margin-top: 80px;
  }

  .page-about .ab-rail {
    position: sticky;
    top: 96px;
    margin-bottom: 0;
    padding-bottom: 0;
    border-bottom: 0;
    border-left: 1px solid var(--c-line);
  }

  .page-about .ab-rail__cap {
    padding-left: 14px;
    margin-bottom: 14px;
  }

  .page-about .ab-rail__list {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about .ab-rail__list > li {
    display: block;
  }

  .page-about .ab-rail__node {
    display: flex;
    margin-left: -1px;
    padding: 12px 0 12px 14px;
    border: 0;
    border-left: 2px solid transparent;
    transition: color .2s var(--ease), border-color .2s var(--ease);
  }

  .page-about .ab-rail__node:hover,
  .page-about .ab-rail__node:focus-visible {
    color: var(--c-white);
    border-left-color: var(--c-amber);
  }

  .page-about .ab-rail__num {
    width: 24px;
    flex: 0 0 auto;
  }

  .page-about .ab-stage {
    padding: 52px 0 64px;
  }

  .page-about .ab-stage__head {
    grid-template-columns: 44px minmax(0, 1fr);
    gap: 22px;
  }

  .page-about .ab-stage__body,
  .page-about .ab-note {
    padding-left: 66px;
  }

  .page-about .ab-note {
    max-width: 38em;
  }

  .page-about .ab-steps {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-rail__node {
    transition: none;
  }
}