.page-about {
  --ab-rail-gap: clamp(40px, 6vw, 88px);
  background: var(--dc-paper);
  color: var(--dc-text);
}

/* ---------- 首屏 ---------- */

.page-about .ab-hero {
  position: relative;
  overflow: hidden;
  background: var(--dc-ink);
  color: var(--dc-warm);
  padding-top: calc(var(--dc-header-h) + clamp(52px, 8vw, 104px));
  padding-bottom: clamp(40px, 6vw, 72px);
}

.page-about .ab-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(113deg,
      rgba(0, 0, 0, 0) calc(58% - 0.5px),
      rgba(196, 85, 45, 0.55) calc(58% - 0.5px),
      rgba(196, 85, 45, 0.55) calc(58% + 0.5px),
      rgba(0, 0, 0, 0) calc(58% + 0.5px)),
    radial-gradient(78% 120% at 100% 0%, rgba(232, 161, 60, 0.13), rgba(232, 161, 60, 0) 58%);
}

.page-about .ab-hero__inner {
  position: relative;
  z-index: 1;
}

.page-about .ab-hero__title {
  margin: clamp(16px, 2.2vw, 28px) 0 0;
  font-family: var(--dc-serif);
  font-weight: 900;
  font-size: clamp(40px, 7vw, 88px);
  line-height: 1.06;
  color: var(--dc-warm);
}

.page-about .ab-hero__lede {
  margin: clamp(20px, 2.6vw, 32px) 0 0;
  max-width: 44em;
  font-size: clamp(16px, 1.2vw, 18px);
  line-height: 1.85;
  color: rgba(244, 239, 230, 0.84);
}

.page-about .ab-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: clamp(32px, 4.4vw, 56px) 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid rgba(201, 214, 211, 0.22);
}

.page-about .ab-stat {
  padding: 18px 0;
  border-bottom: 1px solid rgba(201, 214, 211, 0.22);
}

.page-about .ab-stat__num {
  display: block;
  font-family: var(--dc-mono);
  font-size: clamp(28px, 3.2vw, 42px);
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--dc-warm);
}

.page-about .ab-stat__cap {
  display: block;
  margin-top: 8px;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--dc-amber);
}

/* ---------- 章节索引条 ---------- */

.page-about .ab-toc {
  background: var(--dc-card);
  border-bottom: var(--dc-hair);
}

.page-about .ab-toc__list {
  display: flex;
  align-items: center;
  gap: clamp(16px, 2.6vw, 38px);
  margin: 0;
  padding: 16px 0;
  list-style: none;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.page-about .ab-toc__link {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  white-space: nowrap;
  font-size: 14px;
  line-height: 1.4;
  color: var(--dc-blue);
  text-decoration: none;
  padding-bottom: 3px;
  border-bottom: 1px solid transparent;
  transition: color 0.16s ease, border-color 0.16s ease;
}

.page-about .ab-toc__link:hover,
.page-about .ab-toc__link:focus-visible {
  color: var(--dc-copper);
  border-bottom-color: var(--dc-copper);
}

.page-about .ab-toc__num {
  font-size: 11px;
  color: var(--dc-copper);
}

/* ---------- 通栏扉页图 ---------- */

.page-about .ab-plate {
  position: relative;
  margin: 0;
  background: var(--dc-ink-deep);
  overflow: hidden;
}

.page-about .ab-plate img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: clamp(220px, 36vw, 460px);
  object-fit: cover;
  object-position: center;
  filter: grayscale(1) contrast(1.06);
}

.page-about .ab-plate__cap {
  position: absolute;
  left: clamp(16px, 4vw, 56px);
  bottom: 14px;
  padding: 4px 10px;
  background: rgba(8, 25, 28, 0.74);
  font-family: var(--dc-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: rgba(244, 239, 230, 0.86);
}

/* ---------- 长卷与边注 ---------- */

.page-about .ab-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(36px, 4.6vw, 60px);
  padding: clamp(48px, 7vw, 96px) 0 clamp(24px, 4vw, 48px);
}

.page-about .ab-body__main {
  min-width: 0;
  counter-reset: ab-sec;
}

.page-about .ab-body__rail {
  min-width: 0;
}

.page-about .ab-ch {
  counter-increment: ab-sec;
  border-top: 1px solid var(--dc-line);
  padding-top: clamp(26px, 3vw, 40px);
  margin-top: clamp(40px, 5vw, 68px);
}

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

.page-about .ab-ch__head {
  display: flex;
  align-items: flex-start;
  gap: clamp(14px, 2vw, 24px);
  margin-bottom: clamp(18px, 2.2vw, 28px);
}

.page-about .ab-ch__num {
  flex: 0 0 auto;
  display: block;
  font-family: var(--dc-mono);
  font-size: clamp(42px, 6vw, 86px);
  font-weight: 400;
  line-height: 0.8;
  letter-spacing: 0.01em;
  color: var(--dc-slate);
  opacity: 0.42;
  text-decoration: none;
  transition: color 0.18s ease, opacity 0.18s ease;
}

.page-about .ab-ch__num::before {
  content: counter(ab-sec, decimal-leading-zero);
}

.page-about .ab-ch__num:hover,
.page-about .ab-ch__num:focus-visible {
  color: var(--dc-copper);
  opacity: 1;
}

.page-about .ab-ch__title {
  margin: 0;
  padding-top: clamp(4px, 0.8vw, 10px);
  font-family: var(--dc-serif);
  font-weight: 900;
  font-size: clamp(26px, 3.4vw, 42px);
  line-height: 1.2;
  color: var(--dc-ink);
}

.page-about .ab-p {
  margin: 0 0 1.1em;
  max-width: 38em;
  font-size: 17px;
  line-height: 1.85;
  color: var(--dc-text);
}

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

/* ---------- 阶段列表 ---------- */

.page-about .ab-stages {
  list-style: none;
  margin: clamp(24px, 3vw, 36px) 0 0;
  padding: 0;
  border-bottom: 1px solid var(--dc-line);
}

.page-about .ab-stage {
  display: grid;
  gap: 6px;
  padding: clamp(16px, 1.8vw, 22px) 0;
  border-top: 1px solid var(--dc-line);
}

.page-about .ab-stage__tag {
  margin: 0;
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--dc-copper);
}

.page-about .ab-stage__title {
  margin: 0;
  font-family: var(--dc-sans);
  font-weight: 500;
  font-size: clamp(17px, 1.5vw, 20px);
  line-height: 1.4;
  color: var(--dc-ink);
}

.page-about .ab-stage__text {
  margin: 0;
  max-width: 36em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--dc-text);
}

/* ---------- 正文内嵌图 ---------- */

.page-about .ab-inline-figure {
  margin: clamp(24px, 3vw, 36px) 0 0;
  background: var(--dc-card);
  border: 1px solid var(--dc-line);
}

.page-about .ab-inline-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: clamp(180px, 30vw, 340px);
  object-fit: cover;
  object-position: center;
  filter: grayscale(1) contrast(1.05);
}

.page-about .ab-inline-figure figcaption {
  padding: 10px 14px;
  border-top: 1px solid var(--dc-line);
  font-family: var(--dc-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--dc-blue);
}

/* ---------- 服务要点 ---------- */

.page-about .ab-points {
  list-style: none;
  margin: clamp(20px, 2.6vw, 30px) 0 0;
  padding: 0;
  border-top: 1px solid var(--dc-line);
}

.page-about .ab-point {
  display: grid;
  gap: 6px;
  padding: clamp(14px, 1.6vw, 20px) 0;
  border-bottom: 1px solid var(--dc-line);
}

.page-about .ab-point__k {
  margin: 0;
  font-family: var(--dc-sans);
  font-weight: 500;
  font-size: 15px;
  line-height: 1.5;
  color: var(--dc-ink);
}

.page-about .ab-point__k::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  margin-right: 8px;
  vertical-align: 2px;
  background: var(--dc-copper);
}

.page-about .ab-point__v {
  margin: 0;
  max-width: 36em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--dc-text);
}

/* ---------- 可靠性台账 ---------- */

.page-about .ab-ledger {
  list-style: none;
  margin: clamp(24px, 3vw, 34px) 0 0;
  padding: 0;
}

.page-about .ab-ledger__row {
  display: grid;
  gap: 8px;
  padding: clamp(18px, 2vw, 26px) 0;
  border-top: 1px solid var(--dc-line);
}

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

.page-about .ab-ledger__k {
  margin: 0;
  font-family: var(--dc-sans);
  font-weight: 500;
  font-size: 14px;
  line-height: 1.6;
  color: var(--dc-blue);
}

.page-about .ab-ledger__v {
  margin: 0;
  font-family: var(--dc-mono);
  font-size: clamp(20px, 2.4vw, 28px);
  line-height: 1.3;
  letter-spacing: 0.02em;
  color: var(--dc-ink);
}

.page-about .ab-ledger__d {
  margin: 0;
  max-width: 34em;
  font-size: 15px;
  line-height: 1.7;
  color: var(--dc-blue);
}

/* ---------- 加入与合作 ---------- */

.page-about .ab-paths {
  display: grid;
  gap: clamp(24px, 3vw, 40px);
  margin: clamp(20px, 2.6vw, 30px) 0 clamp(28px, 3.4vw, 40px);
}

.page-about .ab-path {
  border-top: 2px solid var(--dc-copper);
  padding-top: 16px;
}

.page-about .ab-path__tag {
  margin: 0 0 8px;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--dc-copper);
}

.page-about .ab-path__title {
  margin: 0 0 12px;
  font-family: var(--dc-sans);
  font-weight: 500;
  font-size: clamp(17px, 1.5vw, 20px);
  line-height: 1.45;
  color: var(--dc-ink);
}

.page-about .ab-path .ab-p {
  font-size: 16px;
}

/* ---------- 右侧边注 ---------- */

.page-about .ab-rail {
  border-top: 1px solid var(--dc-line);
  padding-top: clamp(20px, 2.4vw, 28px);
}

.page-about .ab-rail__label {
  margin: 0 0 14px;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--dc-amber);
}

.page-about .ab-rail__stats {
  list-style: none;
  margin: 0 0 28px;
  padding: 0;
}

.page-about .ab-rail__stats li {
  padding: 12px 0;
  border-bottom: 1px solid var(--dc-line);
}

.page-about .ab-rail__num {
  display: block;
  font-family: var(--dc-mono);
  font-size: 26px;
  line-height: 1.1;
  letter-spacing: 0.02em;
  color: var(--dc-ink);
}

.page-about .ab-rail__cap {
  display: block;
  margin-top: 4px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--dc-blue);
}

.page-about .ab-rail__meta {
  margin: 0 0 26px;
  font-size: 14px;
  line-height: 1.9;
  color: var(--dc-blue);
}

.page-about .ab-rail__link {
  display: inline-block;
}

/* ---------- 收束 ---------- */

.page-about .ab-coda {
  border-top: 1px solid var(--dc-line);
  padding: clamp(56px, 9vw, 120px) 0 clamp(72px, 11vw, 168px);
}

.page-about .ab-coda__line {
  margin: 0;
  max-width: 22em;
  font-family: var(--dc-serif);
  font-weight: 900;
  font-size: clamp(22px, 3vw, 34px);
  line-height: 1.5;
  color: var(--dc-ink);
}

/* ---------- 断点 ---------- */

@media (min-width: 700px) {
  .page-about .ab-paths {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 720px) {
  .page-about .ab-stage {
    grid-template-columns: 92px minmax(0, 1fr);
    column-gap: 26px;
  }

  .page-about .ab-stage__tag {
    grid-row: 1 / span 2;
    padding-top: 3px;
  }

  .page-about .ab-point {
    grid-template-columns: 180px minmax(0, 1fr);
    column-gap: 24px;
    align-items: baseline;
  }

  .page-about .ab-point__k {
    grid-column: 1;
  }

  .page-about .ab-point__v {
    grid-column: 2;
  }
}

@media (min-width: 780px) {
  .page-about .ab-hero__stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .ab-stat {
    padding: 20px 0 20px 24px;
    border-left: 1px solid rgba(201, 214, 211, 0.22);
  }

  .page-about .ab-stat:first-child {
    padding-left: 0;
    border-left: 0;
  }

  .page-about .ab-ledger__row {
    grid-template-columns: 200px minmax(0, 1fr);
    column-gap: 28px;
    align-items: baseline;
  }

  .page-about .ab-ledger__k {
    grid-column: 1;
    grid-row: 1 / span 2;
  }

  .page-about .ab-ledger__v {
    grid-column: 2;
    grid-row: 1;
  }

  .page-about .ab-ledger__d {
    grid-column: 2;
    grid-row: 2;
  }
}

@media (min-width: 940px) {
  .page-about .ab-body {
    grid-template-columns: minmax(0, 1fr) 272px;
    column-gap: var(--ab-rail-gap);
    align-items: start;
  }

  .page-about .ab-rail {
    position: sticky;
    top: calc(var(--dc-header-h) + 32px);
    border-top: 1px solid var(--dc-copper);
    border-left: 1px solid var(--dc-line);
    padding-left: clamp(20px, 2vw, 28px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-toc__link,
  .page-about .ab-ch__num {
    transition: none;
  }
}
<<<END>>>