.page-about {
  --ab-rail: 112px;
  --ab-gap: clamp(18px, 3.4vw, 44px);
  --ab-paper-dim: #6B6257;
}

/* ---------- 页首纸面 ---------- */
.page-about .ab-masthead {
  background: var(--paper);
  color: var(--paper-ink);
  padding: clamp(20px, 3.4vw, 34px) 0 clamp(40px, 6vw, 76px);
  border-bottom: 1px solid var(--paper-soft);
}

.page-about .breadcrumbs {
  font-family: var(--font-mono);
  font-size: 12px;
  margin-bottom: clamp(28px, 5vw, 52px);
}
.page-about .breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  color: var(--ab-paper-dim);
}
.page-about .breadcrumbs li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--paper-soft);
}
.page-about .breadcrumbs a {
  color: var(--paper-ink);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}
.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  border-bottom-color: var(--red);
}

.page-about .ab-kicker {
  margin: 0 0 18px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--red);
}

.page-about h1 {
  margin: 0;
  max-width: 20ch;
  font-size: clamp(34px, 6.4vw, 76px);
  font-weight: 300;
  line-height: 1.14;
  letter-spacing: -0.02em;
  color: var(--paper-ink);
}

.page-about .ab-lead {
  margin: clamp(24px, 3.6vw, 38px) 0 0;
  max-width: 62ch;
  font-size: clamp(16px, 1.6vw, 18px);
  line-height: 1.85;
  color: #3A342C;
}

.page-about .ab-facts {
  margin: clamp(34px, 5vw, 56px) 0 0;
  padding: clamp(20px, 3vw, 28px) 0 0;
  border-top: 1px solid var(--paper-soft);
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 22px 16px;
}
.page-about .ab-facts li {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.page-about .ab-facts strong {
  font-family: var(--font-mono);
  font-size: clamp(26px, 3.6vw, 42px);
  font-weight: 700;
  line-height: 1;
  color: var(--red);
  font-variant-numeric: tabular-nums;
}
.page-about .ab-facts span {
  font-size: 13px;
  line-height: 1.5;
  color: var(--ab-paper-dim);
}

/* ---------- 章节轨道 ---------- */
.page-about .ab-rail {
  padding: clamp(56px, 8vw, 104px) 0 clamp(40px, 6vw, 72px);
}

.page-about .ab-step {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  padding-bottom: clamp(56px, 8vw, 96px);
}

.page-about .ab-step__mark {
  display: flex;
  align-items: baseline;
  gap: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
}
.page-about .ab-step__no {
  color: var(--orange);
  font-weight: 700;
}
.page-about .ab-step__yr {
  color: var(--index);
}

.page-about .ab-step__body h2 {
  margin: 0 0 10px;
  max-width: 22ch;
  font-size: clamp(27px, 4.2vw, 46px);
  font-weight: 300;
  line-height: 1.2;
  letter-spacing: -0.015em;
  color: var(--white);
}

.page-about .ab-step__sub {
  margin: 0 0 clamp(20px, 3vw, 30px);
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.7;
  color: var(--index);
}

.page-about .ab-step__body > p {
  margin: 0 0 18px;
  max-width: 68ch;
  font-size: 16px;
  line-height: 1.85;
  color: var(--text);
}
.page-about .ab-step__body > p:last-of-type {
  margin-bottom: 0;
}

.page-about .ab-inline-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(24px, 3.6vw, 36px);
}
.page-about .ab-inline-links .btn {
  text-decoration: none;
}

/* ---------- 团队与值守 ---------- */
.page-about .ab-duo {
  margin-top: clamp(28px, 4vw, 44px);
  display: grid;
  grid-template-columns: 1fr;
  gap: 22px;
  align-items: start;
}

.page-about .ab-ring {
  margin: 0;
  padding: 22px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  display: grid;
  gap: 16px;
}
.page-about .ab-ring svg {
  width: 132px;
  height: 132px;
  max-width: 100%;
}
.page-about .ab-ring__track {
  stroke: var(--line);
}
.page-about .ab-ring__arc {
  stroke: var(--lime);
}
.page-about .ab-ring figcaption {
  display: grid;
  gap: 8px;
}
.page-about .ab-ring__num {
  font-family: var(--font-mono);
  font-size: 28px;
  font-weight: 700;
  line-height: 1;
  color: var(--lime);
  font-variant-numeric: tabular-nums;
}
.page-about .ab-ring__tx {
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-dim);
}

.page-about .ab-shot {
  margin: 0;
}
.page-about .ab-shot img,
.page-about .ab-city img,
.page-about .ab-coda img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--radius);
}
.page-about .ab-shot figcaption,
.page-about .ab-city figcaption {
  margin-top: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.7;
  color: var(--index);
}

/* ---------- 版本台阶 ---------- */
.page-about .ab-steps {
  list-style: none;
  margin: clamp(26px, 4vw, 40px) 0 0;
  padding: 0 0 0;
  display: grid;
  grid-template-columns: repeat(7, minmax(0, 1fr));
  gap: 5px;
  align-items: end;
  border-bottom: 1px solid var(--line);
}
.page-about .ab-col {
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: stretch;
  min-height: 200px;
  text-align: center;
}
.page-about .ab-col__bar {
  display: block;
  width: 100%;
  background: var(--panel);
  border: 1px solid var(--line);
  border-bottom: none;
  transition: background 200ms var(--ease), border-color 200ms var(--ease);
}
.page-about .ab-col:nth-child(1) .ab-col__bar { height: 24px; }
.page-about .ab-col:nth-child(2) .ab-col__bar { height: 42px; }
.page-about .ab-col:nth-child(3) .ab-col__bar { height: 60px; }
.page-about .ab-col:nth-child(4) .ab-col__bar { height: 78px; }
.page-about .ab-col:nth-child(5) .ab-col__bar { height: 96px; }
.page-about .ab-col:nth-child(6) .ab-col__bar { height: 116px; }
.page-about .ab-col:nth-child(7) .ab-col__bar {
  height: 142px;
  background: linear-gradient(to top, var(--panel), rgba(183, 255, 46, 0.24));
  border-color: var(--lime);
}
.page-about .ab-col:hover .ab-col__bar,
.page-about .ab-col:focus-within .ab-col__bar {
  background: rgba(255, 107, 26, 0.2);
  border-color: var(--orange);
}
.page-about .ab-col__yr {
  display: block;
  margin-top: 9px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.04em;
  color: var(--index);
}
.page-about .ab-col__nm {
  display: block;
  margin-top: 3px;
  font-size: 12px;
  color: var(--text-dim);
}

/* ---------- 版本明细 ---------- */
.page-about .ab-vlist {
  list-style: none;
  margin: clamp(30px, 4.4vw, 48px) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line);
}
.page-about .ab-vrow {
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr);
  gap: 4px 14px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}
.page-about .ab-vrow__yr {
  grid-row: span 2;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 700;
  color: var(--lime);
  font-variant-numeric: tabular-nums;
}
.page-about .ab-vrow__nm {
  font-size: 15px;
  font-weight: 600;
  color: var(--white);
  letter-spacing: 0.01em;
}
.page-about .ab-vrow__tx {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-dim);
}

/* ---------- 服务范围配图 ---------- */
.page-about .ab-city {
  margin: clamp(30px, 4.4vw, 48px) 0 0;
}

/* ---------- 收束 ---------- */
.page-about .ab-step--end {
  padding-bottom: clamp(40px, 6vw, 72px);
}

.page-about .ab-quote {
  margin: 0 0 clamp(28px, 4vw, 42px);
  padding: 0 0 0 26px;
  border-left: 2px solid var(--orange);
  position: relative;
}
.page-about .ab-quote::before {
  content: "";
  display: block;
  width: 46px;
  height: 3px;
  margin-bottom: 20px;
  background: linear-gradient(90deg, var(--orange), var(--lime));
}
.page-about .ab-quote p {
  margin: 0;
  max-width: 44ch;
  font-size: clamp(19px, 2.4vw, 27px);
  line-height: 1.62;
  font-weight: 300;
  color: var(--white);
}

.page-about .ab-coda {
  margin: 0;
  padding: 0 0 clamp(56px, 8vw, 104px);
}
.page-about .ab-coda img {
  border-radius: 0;
}
.page-about .ab-coda figcaption {
  margin-top: 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--index);
}

/* ---------- 桌面端 ---------- */
@media (min-width: 760px) {
  .page-about .ab-facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 24px;
  }
  .page-about .ab-vrow {
    grid-template-columns: 78px minmax(0, 1fr);
  }
}

@media (min-width: 900px) {
  .page-about .ab-step {
    grid-template-columns: var(--ab-rail) minmax(0, 1fr);
    gap: clamp(28px, 4vw, 52px);
  }
  .page-about .ab-step__mark {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
    position: relative;
    padding-top: 4px;
  }
  .page-about .ab-step__mark::before {
    content: "";
    position: absolute;
    top: 20px;
    bottom: calc(-1 * clamp(56px, 8vw, 96px));
    left: 4px;
    width: 1px;
    background: linear-gradient(to bottom, var(--line), rgba(18, 59, 99, 0.25));
  }
  .page-about .ab-step__mark::after {
    content: "";
    position: absolute;
    top: 6px;
    left: 0;
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: var(--lime);
    box-shadow: 0 0 0 4px rgba(183, 255, 46, 0.12);
  }
  .page-about .ab-step__no {
    padding-left: 0;
  }
  .page-about .ab-step:last-child .ab-step__mark::before {
    bottom: 0;
    background: linear-gradient(to bottom, var(--line), transparent);
  }

  .page-about .ab-duo {
    grid-template-columns: minmax(0, 300px) minmax(0, 1fr);
    gap: 28px;
  }
  .page-about .ab-ring {
    position: sticky;
    top: 128px;
  }
}

@media (min-width: 1100px) {
  .page-about .ab-step__body > p {
    font-size: 17px;
  }
  .page-about .ab-steps {
    gap: 8px;
  }
}

/* ---------- 动效 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-about .ab-col__bar {
    transition: none;
  }
  .page-about [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
  }
}