.page-about {
  --ab-pad-y: clamp(56px, 8vw, 112px);
  --ab-hair: 1px solid var(--line-blue);
  display: block;
}

/* ---------- 开篇 ---------- */
.page-about .ab-open {
  position: relative;
  padding-top: clamp(28px, 5vw, 56px);
}
.page-about .ab-open__inner {
  padding-bottom: clamp(28px, 5vw, 56px);
}
.page-about .ab-open__kicker {
  margin: 0 0 clamp(20px, 3vw, 34px);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.34em;
  color: var(--desert-gold);
}
.page-about .ab-open__title {
  margin: 0;
  max-width: 16ch;
}
.page-about .ab-open__lead {
  margin: clamp(22px, 3vw, 34px) 0 0;
  font-size: clamp(16px, 1.6vw, 19px);
  line-height: 1.9;
  color: var(--sand-white);
}
.page-about .ab-rule {
  height: 1px;
  margin-top: clamp(30px, 4vw, 48px);
  background: linear-gradient(90deg, var(--desert-gold) 0%, rgba(201, 162, 39, 0.22) 38%, rgba(201, 162, 39, 0) 100%);
}
.page-about .ab-open__meta {
  margin: 14px 0 0;
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--rock-grey);
}
.page-about .ab-open__fig {
  margin: 0;
}
.page-about .ab-open__fig img {
  display: block;
  width: 100%;
  height: clamp(200px, 34vh, 400px);
  object-fit: cover;
  border-top: var(--ab-hair);
  border-bottom: var(--ab-hair);
}

/* ---------- 通用区块头间距 ---------- */
.page-about .ab-sechead {
  display: grid;
  gap: 8px;
}
.page-about .ab-sechead .section-note {
  max-width: 42ch;
}

/* ---------- 时间线 ---------- */
.page-about .ab-time {
  padding-top: var(--ab-pad-y);
  padding-bottom: var(--ab-pad-y);
}
.page-about .ab-time__fig {
  margin: clamp(30px, 4vw, 48px) 0 0;
}
.page-about .ab-time__fig img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}
.page-about .ab-rail {
  list-style: none;
  margin: clamp(30px, 4vw, 48px) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
}
.page-about .ab-node {
  position: relative;
  padding: 26px 16px 28px 0;
  border-top: var(--ab-hair);
  transition: transform 0.16s var(--ease), border-color 0.16s var(--ease);
}
.page-about .ab-node::before {
  content: "";
  position: absolute;
  top: -1px;
  left: 0;
  width: 34px;
  height: 3px;
  background: var(--desert-gold);
  transition: width 0.16s var(--ease), background-color 0.16s var(--ease);
}
.page-about .ab-node:hover::before,
.page-about .ab-node:focus-visible::before {
  width: 68px;
  background: var(--volt-cyan);
}
.page-about .ab-node:hover,
.page-about .ab-node:focus-visible {
  transform: translateY(-2px);
  border-top-color: var(--desert-gold);
}
.page-about .ab-node:focus-visible {
  outline: 2px solid var(--volt-cyan);
  outline-offset: 4px;
}
.page-about .ab-node__year {
  display: block;
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--desert-gold);
}
.page-about .ab-node__title {
  margin: 16px 0 8px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--sand-white);
}
.page-about .ab-node__text {
  margin: 0;
  max-width: 30ch;
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-muted);
}
.page-about .ab-node__pop {
  margin: 12px 0 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--rock-grey);
  transition: color 0.16s var(--ease);
}
.page-about .ab-node:hover .ab-node__pop,
.page-about .ab-node:focus-visible .ab-node__pop {
  color: var(--volt-cyan);
}

/* ---------- 分区运营方法 ---------- */
.page-about .ab-method {
  position: relative;
  padding-top: var(--ab-pad-y);
  padding-bottom: var(--ab-pad-y);
  border-top: var(--ab-hair);
}
.page-about .ab-spine-wrap {
  display: none;
}
.page-about .ab-method__grid {
  display: grid;
  gap: clamp(32px, 5vw, 64px);
}
.page-about .ab-method__lead {
  margin: clamp(18px, 2.5vw, 28px) 0 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--text-muted);
}
.page-about .ab-steps {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .ab-step {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 6px 16px;
  padding: 22px 0;
  border-top: var(--ab-hair);
  transition: border-color 0.16s var(--ease);
}
.page-about .ab-step:last-child {
  border-bottom: var(--ab-hair);
}
.page-about .ab-step__num {
  grid-row: 1 / span 2;
  padding-top: 3px;
  font-size: 15px;
  color: var(--desert-gold);
  transition: color 0.16s var(--ease);
}
.page-about .ab-step__title {
  grid-column: 2;
  margin: 0;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--sand-white);
}
.page-about .ab-step p {
  grid-column: 2;
  margin: 0;
  max-width: 44ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-muted);
}
.page-about .ab-step p a {
  color: var(--volt-cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 229, 255, 0.4);
}
.page-about .ab-step:hover,
.page-about .ab-step:focus-visible {
  border-top-color: var(--desert-gold);
}
.page-about .ab-step:hover .ab-step__num,
.page-about .ab-step:focus-visible .ab-step__num {
  color: var(--volt-cyan);
}
.page-about .ab-step:focus-visible {
  outline: 2px solid var(--volt-cyan);
  outline-offset: 4px;
}
.page-about .ab-method__fig {
  margin: clamp(30px, 4vw, 48px) 0 0;
}
.page-about .ab-method__fig img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

/* ---------- 客户端版本节奏 ---------- */
.page-about .ab-client {
  padding-top: var(--ab-pad-y);
  padding-bottom: var(--ab-pad-y);
  border-top: var(--ab-hair);
}
.page-about .ab-client__lead {
  margin: clamp(26px, 3.5vw, 40px) 0 0;
  font-size: 16px;
  line-height: 1.9;
  color: var(--sand-white);
}
.page-about .ab-client__lead a {
  color: var(--volt-cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 229, 255, 0.4);
}
.page-about .ab-client__link {
  margin: clamp(22px, 3vw, 32px) 0 0;
}
.page-about .ab-scroll {
  margin-top: clamp(24px, 3vw, 36px);
  overflow-x: auto;
}
.page-about .ab-spec,
.page-about .ab-duty {
  min-width: 660px;
}
.page-about .ab-spec__caption {
  padding-bottom: 14px;
  text-align: left;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--rock-grey);
}

/* ---------- 团队分工 ---------- */
.page-about .ab-team {
  padding-top: var(--ab-pad-y);
  padding-bottom: var(--ab-pad-y);
  border-top: var(--ab-hair);
}
.page-about .ab-team__lead {
  margin: clamp(24px, 3vw, 36px) 0 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--text-muted);
}

/* ---------- 可信度面板（浅色展签） ---------- */
.page-about .ab-cred {
  color: var(--ink);
  background: var(--paper-white);
}
.page-about .ab-cred__tag {
  display: inline-block;
  margin: 0 0 20px;
  padding: 6px 12px;
  border: 1px solid var(--canyon-800);
  font-size: 11px;
  letter-spacing: 0.26em;
  color: var(--canyon-800);
}
.page-about .ab-cred .section-title,
.page-about .ab-cred .section-note {
  color: var(--ink);
}
.page-about .ab-cred__note {
  max-width: 46ch;
  color: var(--ink-muted);
}
.page-about .ab-cred__grid {
  display: grid;
  gap: 0;
  margin: clamp(26px, 3.5vw, 40px) 0 0;
  border-top: 1px solid rgba(22, 35, 58, 0.28);
}
.page-about .ab-cred__item {
  display: grid;
  grid-template-columns: minmax(88px, 132px) minmax(0, 1fr);
  gap: 4px 18px;
  padding: 16px 0;
  border-bottom: 1px solid rgba(22, 35, 58, 0.16);
}
.page-about .ab-cred__item dt {
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--ink-muted);
}
.page-about .ab-cred__item dd {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--ink);
}
.page-about .ab-cred__foot {
  margin: clamp(22px, 3vw, 30px) 0 0;
  font-size: 13px;
  color: var(--ink-muted);
}
.page-about .ab-cred__foot a {
  color: var(--canyon-800);
  text-decoration: none;
  border-bottom: 1px solid rgba(22, 35, 58, 0.35);
}

/* ---------- 联系渠道定位 ---------- */
.page-about .ab-contact {
  padding-top: var(--ab-pad-y);
  padding-bottom: var(--ab-pad-y);
}
.page-about .ab-contact__grid {
  display: grid;
  gap: clamp(30px, 4vw, 56px);
}
.page-about .ab-contact__intro .measure {
  margin-top: clamp(18px, 2.5vw, 28px);
  font-size: 15px;
  line-height: 1.9;
  color: var(--text-muted);
}
.page-about .ab-channels {
  margin: 0;
  border-top: var(--ab-hair);
}
.page-about .ab-channels > div {
  display: grid;
  grid-template-columns: minmax(84px, 116px) minmax(0, 1fr);
  gap: 6px 18px;
  padding: 15px 0;
  border-bottom: var(--ab-hair);
}
.page-about .ab-channels dt {
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--rock-grey);
}
.page-about .ab-channels dd {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--sand-white);
  word-break: break-word;
}
.page-about .ab-contact__tip {
  margin: clamp(28px, 4vw, 40px) 0 0;
  font-size: 15px;
  line-height: 1.9;
  color: var(--text-muted);
}
.page-about .ab-contact__cta {
  margin: 20px 0 0;
}

/* ---------- 响应式 ---------- */
@media (min-width: 720px) {
  .page-about .ab-cred__grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    column-gap: 48px;
  }
  .page-about .ab-contact__grid {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    align-items: start;
  }
}

@media (min-width: 900px) {
  .page-about .ab-rail {
    grid-template-columns: repeat(5, minmax(0, 1fr));
  }
  .page-about .ab-node {
    padding-right: 26px;
  }
  .page-about .ab-method__grid {
    grid-template-columns: minmax(220px, 4fr) minmax(0, 8fr);
    align-items: stretch;
  }
  .page-about .ab-client__lead,
  .page-about .ab-team__lead {
    max-width: 62ch;
  }
}

@media (min-width: 1180px) {
  .page-about .ab-spine-wrap {
    display: block;
    position: absolute;
    top: 0;
    bottom: 0;
    left: 6px;
    width: 40px;
    pointer-events: none;
  }
  .page-about .ab-spine {
    position: sticky;
    top: 110px;
    margin: 0;
    padding-left: 14px;
    writing-mode: vertical-rl;
    font-size: 11px;
    letter-spacing: 0.32em;
    color: var(--rock-grey);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-node,
  .page-about .ab-node::before,
  .page-about .ab-node__pop,
  .page-about .ab-step,
  .page-about .ab-step__num {
    transition: none;
  }
  .page-about .ab-node:hover,
  .page-about .ab-node:focus-visible {
    transform: none;
  }
}