.page-about {
  --ab-gap: clamp(24px, 3.6vw, 44px);
  --ab-card: linear-gradient(150deg, rgba(22, 38, 74, .95), rgba(11, 27, 58, .95));
  position: relative;
  background:
    radial-gradient(900px 560px at 92% -4%, rgba(108, 63, 197, .30), transparent 60%),
    radial-gradient(760px 520px at -10% 30%, rgba(0, 229, 255, .12), transparent 58%),
    var(--ink-900);
  color: var(--text);
  font-family: var(--font-body);
  overflow-x: clip;
  padding-bottom: clamp(56px, 9vw, 120px);
}

.page-about img {
  display: block;
  max-width: 100%;
  height: auto;
}

.page-about .media-frame img {
  width: 100%;
  object-fit: cover;
}

.page-about .ab-figure {
  margin: 0;
  clip-path: var(--cut);
  background: var(--ink-700);
  border: 1px solid var(--line);
}

/* ---------- 首屏 ---------- */
.page-about .ab-head {
  padding: clamp(40px, 7vw, 88px) 0 clamp(28px, 4vw, 52px);
}

.page-about .ab-head h1 {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(30px, 6vw, 56px);
  line-height: 1.16;
  letter-spacing: .005em;
  margin: .32em 0 .48em;
  max-width: 19ch;
}

.page-about .ab-lede {
  font-size: 17px;
  line-height: 1.9;
  color: var(--text-dim);
  max-width: 66ch;
  margin: 0;
}

.page-about .ab-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 36px 0 0;
}

.page-about .ab-stat {
  position: relative;
  margin: 0;
  padding: 16px 16px 15px 20px;
  background: var(--ab-card);
  clip-path: var(--cut-sm);
}

.page-about .ab-stat::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--violet), var(--cyan));
}

.page-about .ab-stat-num {
  margin: 0;
  font-family: var(--font-mono);
  font-size: clamp(21px, 3vw, 28px);
  font-weight: 700;
  letter-spacing: -.03em;
  font-variant-numeric: tabular-nums;
  color: var(--cyan);
  line-height: 1.05;
}

.page-about .ab-stat--amber .ab-stat-num {
  color: var(--amber);
}

.page-about .ab-stat-label {
  display: block;
  margin-top: 7px;
  font-size: 13px;
  color: var(--text-dim);
  line-height: 1.5;
}

/* ---------- 通用章节 ---------- */
.page-about .ab-sec {
  padding: clamp(52px, 8vw, 96px) 0 0;
}

.page-about .ab-sec-idx {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .2em;
  color: var(--cyan);
  margin: 0 0 14px;
}

.page-about .ab-sec-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(26px, 4.2vw, 40px);
  line-height: 1.24;
  margin: 0 0 18px;
  max-width: 26ch;
}

.page-about .ab-copy {
  font-size: 17px;
  line-height: 1.88;
  color: var(--text-dim);
  max-width: 68ch;
  margin: 0 0 1.05em;
}

.page-about .ab-copy--wide {
  max-width: 78ch;
}

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

/* ---------- 起点：非对称分栏 ---------- */
.page-about .ab-sec--split {
  display: grid;
  gap: clamp(22px, 4vw, 44px);
}

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

.page-about .ab-side-list li {
  font-size: 15px;
  line-height: 1.75;
  color: var(--text-dim);
  padding: 11px 0 11px 20px;
  position: relative;
  border-bottom: 1px solid var(--line);
}

.page-about .ab-side-list li:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.page-about .ab-side-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 19px;
  width: 7px;
  height: 7px;
  background: var(--violet);
  clip-path: var(--cut-sm);
}

/* ---------- 02 时间轴 ---------- */
.page-about .ab-timeline {
  list-style: none;
  margin: clamp(28px, 4vw, 48px) 0 0;
  padding: 0;
  position: relative;
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 8px;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: linear-gradient(180deg, var(--violet), var(--cyan));
  opacity: .75;
}

.page-about .ab-tl-item {
  position: relative;
  padding-left: 46px;
  margin-bottom: var(--ab-gap);
}

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

.page-about .ab-tl-node {
  position: absolute;
  left: 0;
  top: 26px;
  width: 18px;
  height: 18px;
  background: linear-gradient(135deg, var(--violet), var(--cyan));
  clip-path: var(--cut-sm);
  z-index: 1;
}

.page-about .ab-tl-card {
  position: relative;
  padding: 22px 20px 20px;
  background: var(--ab-card);
  clip-path: var(--cut);
}

.page-about .ab-tl-card::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: linear-gradient(180deg, var(--violet), var(--cyan));
}

.page-about .ab-tl-card::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 2px;
  background: var(--cyan);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform .45s var(--ease);
}

.page-about .ab-tl-card:hover::after,
.page-about .ab-tl-card:focus-within::after {
  transform: scaleX(1);
}

.page-about .ab-tl-ver {
  font-family: var(--font-mono);
  font-size: clamp(28px, 4.6vw, 40px);
  font-weight: 700;
  letter-spacing: -.04em;
  line-height: 1;
  color: var(--text);
  margin: 0 0 10px;
  font-variant-numeric: tabular-nums;
}

.page-about .ab-tl-stage {
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .12em;
  color: var(--amber);
  margin: 0 0 12px;
}

.page-about .ab-tl-h3 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(19px, 2.4vw, 23px);
  line-height: 1.4;
  margin: 0 0 10px;
}

.page-about .ab-tl-text {
  font-size: 16px;
  line-height: 1.82;
  color: var(--text-dim);
  margin: 0;
}

.page-about .ab-tl-more {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.page-about .ab-tl-more summary {
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--cyan);
  min-height: 24px;
}

.page-about .ab-tl-more summary::-webkit-details-marker {
  display: none;
}

.page-about .ab-tl-more summary::after {
  content: " +";
}

.page-about .ab-tl-more[open] summary::after {
  content: " –";
}

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

.page-about .ab-tl-list {
  margin: 12px 0 0;
  padding-left: 18px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-dim);
}

.page-about .ab-tl-list li {
  margin-bottom: 6px;
}

.page-about .ab-tl-list li::marker {
  color: var(--violet);
}

/* ---------- 03 归档 ---------- */
.page-about .ab-archive {
  display: grid;
  gap: clamp(22px, 3.5vw, 40px);
  margin-top: clamp(24px, 3.5vw, 40px);
}

.page-about .ab-layers {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .ab-layer {
  padding: 18px 18px 18px 20px;
  background: var(--ab-card);
  border-left: 2px solid var(--line);
}

.page-about .ab-layer-key {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--violet);
  display: block;
  margin-bottom: 8px;
}

.page-about .ab-layer-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  line-height: 1.4;
  margin: 0 0 8px;
}

.page-about .ab-layer p {
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
  margin: 0;
}

/* ---------- 04 团队 ---------- */
.page-about .ab-team {
  display: grid;
  gap: clamp(22px, 3.5vw, 40px);
  margin-top: clamp(24px, 3.5vw, 40px);
}

.page-about .ab-roles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .ab-role {
  padding: 18px 18px 18px 20px;
  background: var(--ab-card);
  clip-path: var(--cut-sm);
  position: relative;
  transition: background .3s var(--ease);
}

.page-about .ab-role::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--line);
  transition: background .3s var(--ease);
}

.page-about .ab-role:hover::before,
.page-about .ab-role:focus-visible::before {
  background: linear-gradient(180deg, var(--violet), var(--cyan));
}

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

.page-about .ab-role-name {
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: .06em;
  color: var(--text);
  margin: 0 0 8px;
  font-weight: 600;
}

.page-about .ab-role-desc {
  font-size: 15px;
  line-height: 1.78;
  color: var(--text-dim);
  margin: 0;
}

.page-about .ab-rhythm {
  list-style: none;
  margin: clamp(22px, 3.5vw, 36px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.page-about .ab-rhythm-item {
  padding: 16px 16px 15px;
  background: rgba(22, 38, 74, .6);
  border-top: 2px solid var(--cyan);
}

.page-about .ab-rhythm-item--amber {
  border-top-color: var(--amber);
}

.page-about .ab-rhythm-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(20px, 2.8vw, 26px);
  font-weight: 700;
  letter-spacing: -.03em;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
  line-height: 1.1;
}

.page-about .ab-rhythm-item--amber .ab-rhythm-num {
  color: var(--amber);
}

.page-about .ab-rhythm-label {
  display: block;
  margin-top: 7px;
  font-size: 13px;
  line-height: 1.5;
  color: var(--text-dim);
}

/* ---------- 05 服务范围 ---------- */
.page-about .ab-reach {
  list-style: none;
  margin: clamp(22px, 3.5vw, 36px) 0 clamp(24px, 3.5vw, 36px);
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.page-about .ab-reach-item {
  padding: 18px 16px;
  background: linear-gradient(160deg, rgba(108, 63, 197, .22), rgba(11, 27, 58, .9));
  clip-path: var(--cut-sm);
}

.page-about .ab-reach-num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.6vw, 34px);
  font-weight: 700;
  letter-spacing: -.04em;
  color: var(--text);
  font-variant-numeric: tabular-nums;
  line-height: 1.05;
}

.page-about .ab-reach-item--amber .ab-reach-num {
  color: var(--amber);
}

.page-about .ab-reach-label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.5;
  color: var(--text-dim);
}

/* ---------- 06 接下来 ---------- */
.page-about .ab-next {
  list-style: none;
  counter-reset: abnext;
  margin: clamp(24px, 3.5vw, 40px) 0 0;
  padding: 0;
  display: grid;
  gap: clamp(20px, 3vw, 32px);
}

.page-about .ab-next-item {
  position: relative;
  counter-increment: abnext;
  padding-left: 68px;
}

.page-about .ab-next-item::before {
  content: "0" counter(abnext);
  position: absolute;
  left: 0;
  top: -4px;
  font-family: var(--font-mono);
  font-size: 34px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.04em;
  color: transparent;
  -webkit-text-stroke: 1px var(--violet);
}

.page-about .ab-next-name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(18px, 2.2vw, 22px);
  line-height: 1.42;
  margin: 0 0 8px;
}

.page-about .ab-next-item p {
  font-size: 16px;
  line-height: 1.82;
  color: var(--text-dim);
  margin: 0;
  max-width: 62ch;
}

/* ---------- 收尾 ---------- */
.page-about .ab-cta {
  margin-top: clamp(52px, 8vw, 96px);
  padding: clamp(28px, 4.5vw, 52px) clamp(22px, 4vw, 52px);
  background:
    linear-gradient(140deg, rgba(108, 63, 197, .32), rgba(5, 11, 28, .92) 62%),
    var(--ink-800);
  clip-path: var(--cut);
  border-top: 2px solid transparent;
}

.page-about .ab-cta-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(24px, 3.6vw, 34px);
  line-height: 1.25;
  margin: 0 0 14px;
}

.page-about .ab-cta-text {
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--text-dim);
  max-width: 62ch;
  margin: 0 0 24px;
}

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

.page-about .ab-cta-note {
  margin: 22px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-dim);
}

.page-about .ab-cta-note a {
  color: var(--cyan);
  text-underline-offset: 3px;
}

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

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

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

@media (min-width: 900px) {
  .page-about .ab-sec--split {
    grid-template-columns: 7fr 4fr;
    align-items: start;
  }

  .page-about .ab-archive {
    grid-template-columns: 7fr 5fr;
    align-items: start;
  }

  .page-about .ab-team {
    grid-template-columns: 1.05fr .95fr;
    align-items: start;
  }

  .page-about .ab-rhythm {
    margin-top: clamp(28px, 4vw, 44px);
  }

  /* 时间轴改为中线左右交错 */
  .page-about .ab-timeline::before {
    left: 50%;
    margin-left: -1px;
    top: 10px;
    bottom: 10px;
  }

  .page-about .ab-tl-item {
    width: calc(50% - 46px);
    padding-left: 0;
    margin-bottom: clamp(32px, 4vw, 52px);
  }

  .page-about .ab-tl-item:nth-child(odd) {
    margin-right: auto;
  }

  .page-about .ab-tl-item:nth-child(even) {
    margin-left: auto;
  }

  .page-about .ab-tl-item:nth-child(odd) .ab-tl-node {
    left: auto;
    right: -55px;
  }

  .page-about .ab-tl-item:nth-child(even) .ab-tl-node {
    left: -55px;
  }

  .page-about .ab-tl-card {
    padding: 26px 26px 24px;
  }
}

@media (min-width: 1080px) {
  .page-about .ab-head {
    padding-top: clamp(56px, 7vw, 104px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-tl-card::after,
  .page-about .ab-role::before,
  .page-about .ab-role {
    transition: none;
  }
}