.page-about {
  --ab-rail: 116px;
  --ab-body: 64ch;
  --ab-sec-pad: clamp(56px, 8vw, 104px);
  display: block;
  background-color: var(--ink-900);
  color: var(--paper);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .ab-hero {
  position: relative;
  padding: clamp(44px, 8vw, 100px) 0 clamp(42px, 6vw, 80px);
  background:
    radial-gradient(920px 520px at 88% -20%, rgba(43, 224, 200, 0.18), transparent 60%),
    radial-gradient(720px 480px at -12% 32%, rgba(58, 42, 114, 0.55), transparent 66%);
}

.page-about .ab-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--cyan), var(--violet) 52%, var(--gold));
  opacity: 0.9;
}

.page-about .ab-hero h1 {
  font-family: var(--font-head);
  font-size: clamp(30px, 5.2vw, 56px);
  line-height: 1.14;
  letter-spacing: -0.02em;
  margin: 16px 0 0;
  max-width: 20ch;
}

.page-about .ab-hero .lede {
  margin: 22px 0 0;
  max-width: 62ch;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.8;
  color: rgba(233, 237, 249, 0.86);
}

.page-about .ab-facts {
  list-style: none;
  margin: clamp(28px, 4vw, 48px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.page-about .ab-facts li {
  background: rgba(20, 28, 78, 0.78);
  padding: 20px 18px 22px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .ab-fact__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(22px, 3vw, 32px);
  line-height: 1.1;
  color: var(--cyan);
  letter-spacing: -0.01em;
}

.page-about .ab-fact__label {
  font-size: 14px;
  line-height: 1.6;
  color: var(--muted);
}

/* ---------- 侧栏章节导航 ---------- */
.page-about .ab-toc {
  display: none;
}

.page-about .ab-toc__label {
  margin: 0 0 10px 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--muted);
}

/* ---------- 章节骨架 ---------- */
.page-about .ab-sec {
  position: relative;
  padding: var(--ab-sec-pad) 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .ab-sec--narrow {
  padding: clamp(44px, 6vw, 76px) 0;
}

.page-about .ab-sec--close {
  background:
    radial-gradient(760px 420px at 8% 110%, rgba(58, 42, 114, 0.5), transparent 62%),
    linear-gradient(180deg, rgba(20, 28, 78, 0.5), rgba(10, 16, 48, 0));
}

.page-about .ab-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 18px;
}

.page-about .ab-rail {
  display: flex;
  align-items: baseline;
  gap: 14px;
}

.page-about .ab-no {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.12em;
  color: var(--cyan);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-pill);
  padding: 4px 12px;
  white-space: nowrap;
}

.page-about .ab-rail__tick {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--muted);
  letter-spacing: 0.04em;
}

.page-about .ab-body {
  max-width: var(--ab-body);
}

.page-about .ab-body h2 {
  font-family: var(--font-head);
  font-size: clamp(24px, 3.6vw, 38px);
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
}

.page-about .ab-body > p {
  font-size: 17px;
  line-height: 1.78;
  color: rgba(233, 237, 249, 0.84);
  margin: 0 0 18px;
}

.page-about .ab-body a {
  color: var(--cyan-soft);
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 1px;
}

.page-about .ab-body a:hover {
  color: var(--cyan);
}

.page-about .ab-note {
  font-size: 15px;
  line-height: 1.75;
  color: var(--muted);
  margin-top: 22px;
  padding-left: 16px;
  border-left: 2px solid var(--line-strong);
}

/* ---------- 时间轴 ---------- */
.page-about .ab-timeline {
  list-style: none;
  margin: 34px 0 0;
  padding: 0 0 0 26px;
  position: relative;
}

.page-about .ab-timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 12px;
  width: 2px;
  background: linear-gradient(180deg, var(--cyan), var(--violet) 58%, rgba(58, 42, 114, 0));
}

.page-about .ab-timeline li {
  position: relative;
  padding: 0 0 30px;
}

.page-about .ab-timeline li::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 5px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 0 4px rgba(43, 224, 200, 0.14);
}

.page-about .ab-timeline li:nth-child(2)::before {
  width: 16px;
  height: 16px;
  left: -28px;
  background: var(--cyan-soft);
}

.page-about .ab-timeline li:nth-child(3)::before {
  width: 14px;
  height: 14px;
  left: -27px;
  background: var(--gold);
  box-shadow: 0 0 0 4px rgba(244, 179, 76, 0.16);
}

.page-about .ab-timeline li:nth-child(4)::before {
  width: 10px;
  height: 10px;
  left: -25px;
  background: var(--violet);
  box-shadow: 0 0 0 4px rgba(58, 42, 114, 0.4);
}

.page-about .ab-timeline__stage {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.page-about .ab-timeline h3 {
  font-family: var(--font-head);
  font-size: 20px;
  line-height: 1.35;
  margin: 8px 0 8px;
  letter-spacing: -0.01em;
}

.page-about .ab-timeline p {
  margin: 0;
  font-size: 16px;
  line-height: 1.75;
  color: rgba(233, 237, 249, 0.8);
}

.page-about .ab-timeline__tip {
  display: block;
  margin-top: 0;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--cyan-soft);
  transition: max-height 0.24s var(--ease), opacity 0.24s var(--ease), margin-top 0.24s var(--ease);
}

.page-about .ab-timeline li:hover .ab-timeline__tip,
.page-about .ab-timeline li:focus-within .ab-timeline__tip {
  max-height: 90px;
  opacity: 1;
  margin-top: 8px;
}

/* ---------- 三条主线 ---------- */
.page-about .ab-lines {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin-top: 30px;
  background: var(--line);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.page-about .ab-line {
  background: rgba(20, 28, 78, 0.8);
  padding: clamp(22px, 3vw, 32px);
}

.page-about .ab-line__idx {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--gold);
}

.page-about .ab-line h3 {
  font-family: var(--font-head);
  font-size: 21px;
  line-height: 1.35;
  margin: 12px 0 10px;
}

.page-about .ab-line p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.75;
  color: rgba(233, 237, 249, 0.8);
}

/* ---------- 两档对比矩阵 ---------- */
.page-about .ab-tierfigure {
  margin: clamp(28px, 4vw, 44px) 0 0;
}

.page-about .ab-matrix {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 20px;
  margin-top: clamp(26px, 4vw, 40px);
}

.page-about .ab-tier {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: clamp(22px, 3vw, 34px);
  background: rgba(20, 28, 78, 0.7);
}

.page-about .ab-tier--home {
  background: linear-gradient(158deg, rgba(43, 224, 200, 0.13), rgba(20, 28, 78, 0.82) 62%);
}

.page-about .ab-tier--biz {
  background: linear-gradient(158deg, rgba(244, 179, 76, 0.15), rgba(20, 28, 78, 0.84) 62%);
}

.page-about .ab-tier__head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
}

.page-about .ab-tier__sub {
  font-size: 14px;
  color: var(--muted);
}

.page-about .ab-pill {
  display: inline-flex;
  align-items: center;
  padding: 6px 16px;
  border-radius: var(--radius-pill);
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0.04em;
}

.page-about .ab-pill--cyan {
  color: var(--cyan-soft);
  background: rgba(43, 224, 200, 0.14);
  border: 1px solid rgba(43, 224, 200, 0.42);
}

.page-about .ab-pill--gold {
  color: var(--gold-soft);
  background: rgba(244, 179, 76, 0.14);
  border: 1px solid rgba(244, 179, 76, 0.44);
}

.page-about .ab-tier dl {
  margin: 22px 0 0;
}

.page-about .ab-tier dl > div {
  display: grid;
  grid-template-columns: 38% minmax(0, 1fr);
  gap: 12px;
  padding: 14px 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .ab-tier dt {
  font-size: 15px;
  color: var(--muted);
}

.page-about .ab-tier dd {
  margin: 0;
  font-size: 16px;
  line-height: 1.6;
  color: var(--paper);
}

/* ---------- 条款库 ---------- */
.page-about .ab-lib {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  margin-top: 26px;
}

.page-about .ab-lib__item {
  border-left: 3px solid var(--cyan);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  background: rgba(20, 28, 78, 0.6);
  padding: 18px 20px;
}

.page-about .ab-lib__key {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--cyan);
  margin-bottom: 8px;
}

.page-about .ab-lib__item p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.72;
  color: rgba(233, 237, 249, 0.82);
}

/* ---------- 团队 ---------- */
.page-about .ab-teamfigure {
  margin: clamp(26px, 4vw, 42px) 0 0;
}

.page-about .ab-team {
  list-style: none;
  margin: clamp(26px, 4vw, 38px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 20px;
}

.page-about .ab-team li {
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: rgba(20, 28, 78, 0.62);
  padding: clamp(20px, 3vw, 26px);
}

.page-about .ab-team__num {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 38px;
  line-height: 1;
  color: var(--cyan);
}

.page-about .ab-team h3 {
  font-family: var(--font-head);
  font-size: 19px;
  margin: 14px 0 8px;
  letter-spacing: -0.01em;
}

.page-about .ab-team p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.74;
  color: rgba(233, 237, 249, 0.8);
}

.page-about .ab-bar {
  display: block;
  height: 6px;
  border-radius: 3px;
  background: rgba(154, 166, 206, 0.22);
  overflow: hidden;
  margin-top: 18px;
}

.page-about .ab-bar__fill {
  display: block;
  height: 100%;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--cyan), var(--violet));
}

.page-about .ab-bar__fill--a {
  width: 18%;
}

.page-about .ab-bar__fill--b {
  width: 28%;
}

.page-about .ab-bar__fill--c {
  width: 39%;
}

/* ---------- 服务网络 ---------- */
.page-about .ab-net {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--line-soft);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.page-about .ab-net li {
  background: rgba(11, 63, 69, 0.68);
  padding: 20px 22px;
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.page-about .ab-net__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 24px;
  color: var(--gold-soft);
  white-space: nowrap;
}

.page-about .ab-net__txt {
  font-size: 15px;
  color: rgba(233, 237, 249, 0.84);
}

/* ---------- 客户关切 ---------- */
.page-about .ab-concerns {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
}

.page-about .ab-concerns li {
  border-top: 1px solid var(--line-soft);
  padding: 22px 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 8px;
}

.page-about .ab-concerns li:last-child {
  border-bottom: 1px solid var(--line-soft);
}

.page-about .ab-concerns__no {
  font-family: var(--font-mono);
  font-size: 14px;
  letter-spacing: 0.14em;
  color: var(--cyan);
}

.page-about .ab-concerns h3 {
  font-family: var(--font-head);
  font-size: 20px;
  line-height: 1.4;
  margin: 0 0 10px;
}

.page-about .ab-concerns p {
  margin: 0;
  font-size: 16px;
  line-height: 1.76;
  color: rgba(233, 237, 249, 0.82);
}

.page-about .ab-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(28px, 4vw, 40px);
}

.page-about .ab-cta .btn {
  flex: 0 0 auto;
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 760px) {
  .page-about .ab-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

  .page-about .ab-concerns li {
    grid-template-columns: 68px minmax(0, 1fr);
    gap: 22px;
    padding: 26px 0;
  }

  .page-about .ab-concerns__no {
    padding-top: 6px;
  }
}

@media (min-width: 900px) {
  .page-about .ab-row {
    grid-template-columns: var(--ab-rail) minmax(0, 1fr);
    gap: clamp(24px, 4vw, 56px);
  }

  .page-about .ab-rail {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
    position: sticky;
    top: calc(var(--header-h-sm) + 28px);
    align-self: start;
  }

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

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

  .page-about .ab-matrix {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 26px;
  }

  .page-about .ab-tier--biz {
    margin-top: 44px;
  }

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

@media (min-width: 1320px) {
  .page-about .ab-toc {
    display: block;
    position: fixed;
    right: 26px;
    top: 50%;
    transform: translateY(-50%);
    width: 132px;
    z-index: 5;
  }

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

  .page-about .ab-toc a {
    display: block;
    padding: 7px 0 7px 14px;
    margin-left: -1px;
    border-left: 2px solid transparent;
    font-size: 13px;
    line-height: 1.4;
    color: var(--muted);
    text-decoration: none;
    transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
  }

  .page-about .ab-toc a:hover {
    color: var(--paper);
  }

  .page-about .ab-toc a[aria-current="true"] {
    color: var(--cyan);
    border-left-color: var(--cyan);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-timeline__tip,
  .page-about .ab-toc a {
    transition: none;
  }
}