.page-about {
  --ab-ink: var(--cool-white);
  --ab-mute: var(--mist-gray);
  --ab-line: var(--grid-line);
  background: var(--night-base);
  color: var(--cool-white);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  padding-bottom: clamp(40px, 7vw, 88px);
}

/* ---- 面包屑 ---- */
.page-about .ab-crumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.55em;
  padding-top: clamp(16px, 3vw, 28px);
  font-size: 12px;
  letter-spacing: 0.12em;
}
.page-about .ab-crumbs a {
  color: var(--mist-gray);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}
.page-about .ab-crumbs a:hover {
  color: var(--neon-green);
  border-bottom-color: var(--neon-green);
}
.page-about .ab-crumbs__sep {
  color: var(--grid-line);
}
.page-about .ab-crumbs__here {
  color: var(--cool-white);
}

/* ---- 首屏 ---- */
.page-about .ab-hero {
  display: grid;
  gap: clamp(22px, 4vw, 40px);
  padding-block: clamp(16px, 3vw, 28px) clamp(36px, 6vw, 72px);
}
.page-about .ab-hero__title {
  margin: 0.5rem 0 0;
  font-size: clamp(34px, 6vw, 76px);
  line-height: 0.98;
  letter-spacing: -0.02em;
  font-weight: 800;
  color: var(--cool-white);
  transform: skewX(-3deg);
  transform-origin: left bottom;
  text-wrap: balance;
  padding-right: 0.15em;
}
.page-about .ab-hero__intro {
  margin: clamp(14px, 2.2vw, 22px) 0 0;
  max-width: 48ch;
  font-size: clamp(15px, 1.5vw, 17px);
  line-height: 1.85;
  color: var(--mist-gray);
}
.page-about .ab-hero__figure {
  margin: 0;
  position: relative;
  overflow: hidden;
  border: 1px solid var(--grid-line);
  background: var(--pitch-shadow);
  aspect-ratio: 16 / 11;
  clip-path: polygon(0 0, 100% 0, 100% 88%, 0 100%);
}
.page-about .ab-hero__figure img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}

/* ---- 章节骨架 ---- */
.page-about .ab-chapter {
  display: grid;
  gap: clamp(14px, 2.5vw, 24px);
  padding-block: clamp(32px, 6vw, 68px);
  border-top: 5px solid var(--paper-warm);
}
.page-about .ab-chapter__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(40px, 7vw, 80px);
  line-height: 0.88;
  letter-spacing: 0.02em;
  color: var(--neon-green);
}
.page-about .ab-chapter__rule {
  margin: clamp(10px, 2vw, 16px) 0 0;
  max-width: 22ch;
  padding-left: 12px;
  border-left: 2px solid var(--electric-orange);
  font-size: 13px;
  line-height: 1.7;
  color: var(--mist-gray);
}
.page-about .ab-chapter__title {
  margin: 0;
  font-size: clamp(23px, 3.4vw, 40px);
  line-height: 1.16;
  letter-spacing: -0.01em;
  font-weight: 800;
  color: var(--cool-white);
  transform: skewX(-3deg);
  transform-origin: left center;
  padding-right: 0.12em;
}
.page-about .ab-chapter__lead {
  margin: clamp(14px, 2.4vw, 22px) 0 0;
  max-width: 58ch;
  font-size: clamp(15px, 1.5vw, 17px);
  line-height: 1.85;
  color: var(--mist-gray);
}
.page-about .ab-chapter__note {
  margin: clamp(14px, 2.4vw, 20px) 0 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist-gray);
}

/* ---- 01 三条标准 ---- */
.page-about .ab-crit {
  list-style: none;
  margin: clamp(22px, 3.5vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: clamp(16px, 2.2vw, 22px);
}
.page-about .ab-crit__item {
  display: grid;
  grid-template-columns: clamp(26px, 6vw, 44px) minmax(0, 1fr);
  gap: clamp(12px, 2vw, 22px);
  padding-top: clamp(14px, 2vw, 20px);
  border-top: 1px solid var(--grid-line);
}
.page-about .ab-crit__no {
  font-family: var(--font-mono);
  font-size: clamp(17px, 2vw, 21px);
  line-height: 1.4;
  letter-spacing: 0.04em;
  color: var(--neon-green);
}
.page-about .ab-crit__name {
  margin: 0 0 6px;
  font-size: clamp(16px, 1.8vw, 20px);
  font-weight: 700;
  line-height: 1.35;
  color: var(--cool-white);
}
.page-about .ab-crit__text {
  margin: 0;
  max-width: 52ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist-gray);
}

/* ---- 02 四级阶梯 ---- */
.page-about .ab-tiers {
  margin: clamp(22px, 3.5vw, 36px) 0 0;
  display: grid;
  gap: 8px;
}
.page-about .ab-tier {
  border: 1px solid var(--grid-line);
  background: var(--pitch-shadow);
  transition: border-color 0.25s var(--ease);
}
.page-about .ab-tier:nth-child(2) { width: 94%; }
.page-about .ab-tier:nth-child(3) { width: 88%; }
.page-about .ab-tier:nth-child(4) { width: 82%; }
.page-about .ab-tier[open] {
  border-color: var(--neon-green);
}
.page-about .ab-tier__head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  cursor: pointer;
  list-style: none;
}
.page-about .ab-tier__head::-webkit-details-marker { display: none; }
.page-about .ab-tier__head:focus-visible {
  outline: 2px solid var(--neon-green);
  outline-offset: 2px;
}
.page-about .ab-tier__idx {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--electric-orange);
  border: 1px solid currentColor;
  padding: 1px 6px;
  line-height: 1.5;
}
.page-about .ab-tier__name {
  font-size: 15px;
  font-weight: 700;
  color: var(--cool-white);
}
.page-about .ab-tier__count {
  font-family: var(--font-mono);
  font-size: 15px;
  letter-spacing: 0.04em;
  color: var(--neon-green);
}
.page-about .ab-tier__desc {
  margin: 0;
  padding: 12px 14px 14px;
  border-top: 1px dashed var(--grid-line);
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist-gray);
}

/* ---- 通用配图 ---- */
.page-about .ab-figure {
  margin: clamp(22px, 3.5vw, 36px) 0 0;
  position: relative;
  overflow: hidden;
  border: 1px solid var(--grid-line);
  background: var(--pitch-shadow);
}
.page-about .ab-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}
.page-about .ab-figure--wide img {
  aspect-ratio: 14 / 9;
}
.page-about .ab-figure__cap {
  padding: 10px 14px;
  border-top: 1px solid var(--grid-line);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--mist-gray);
  background: rgba(8, 13, 24, 0.65);
}

/* ---- 03 更新节奏 ---- */
.page-about .ab-facts {
  margin: clamp(22px, 3.5vw, 36px) 0 0;
  display: grid;
}
.page-about .ab-facts__row {
  display: grid;
  gap: 4px;
  padding-block: clamp(14px, 2vw, 20px);
  border-top: 1px solid var(--grid-line);
}
.page-about .ab-facts dt {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--neon-green);
}
.page-about .ab-facts dd {
  margin: 0;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist-gray);
}

/* ---- 引述块 ---- */
.page-about .ab-quote {
  position: relative;
  background: var(--paper-warm);
  color: var(--night-base);
  padding-block: clamp(30px, 6vw, 76px);
}
.page-about .ab-quote::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 8px;
  background: var(--electric-orange);
}
.page-about .ab-quote__inner {
  display: grid;
  gap: clamp(12px, 2.2vw, 20px);
}
.page-about .ab-quote__text {
  margin: 0;
  max-width: 42ch;
  font-size: clamp(19px, 2.6vw, 30px);
  font-weight: 700;
  line-height: 1.5;
  letter-spacing: -0.005em;
  color: var(--night-base);
}
.page-about .ab-quote__sign {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--deep-green);
}

/* ---- 04 时间轴 ---- */
.page-about .ab-timeline {
  list-style: none;
  margin: clamp(22px, 3.5vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: clamp(18px, 3vw, 26px);
}
.page-about .ab-timeline__item {
  position: relative;
  padding-top: clamp(16px, 2.4vw, 22px);
  border-top: 3px solid var(--grid-line);
}
.page-about .ab-timeline__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: -6px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--grid-line);
}
.page-about .ab-timeline__item--done { border-top-color: var(--deep-green); }
.page-about .ab-timeline__item--done::before { background: var(--deep-green); }
.page-about .ab-timeline__item--now { border-top-color: var(--electric-orange); }
.page-about .ab-timeline__item--now::before { background: var(--electric-orange); }
.page-about .ab-timeline__stage {
  display: inline-block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--mist-gray);
}
.page-about .ab-timeline__name {
  margin: 0 0 6px;
  font-size: clamp(15px, 1.7vw, 18px);
  font-weight: 700;
  line-height: 1.35;
  color: var(--cool-white);
}
.page-about .ab-timeline__item p {
  margin: 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--mist-gray);
}

/* ---- 数据格子 ---- */
.page-about .ab-stats {
  margin: clamp(24px, 4vw, 38px) 0 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--grid-line);
  border: 1px solid var(--grid-line);
}
.page-about .ab-stats__cell {
  display: grid;
  gap: 6px;
  padding: clamp(14px, 2.4vw, 22px);
  background: var(--night-base);
}
.page-about .ab-stats__num {
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.4vw, 34px);
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--neon-green);
}
.page-about .ab-stats__unit {
  margin-left: 2px;
  font-size: 0.5em;
  color: var(--mist-gray);
}
.page-about .ab-stats__key {
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--mist-gray);
}

/* ---- 06 场边清单 ---- */
.page-about .ab-lines {
  list-style: none;
  margin: clamp(22px, 3.5vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: clamp(14px, 2.2vw, 20px);
}
.page-about .ab-lines li {
  position: relative;
  padding-left: 26px;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist-gray);
}
.page-about .ab-lines li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 14px;
  height: 2px;
  background: var(--electric-orange);
}

/* ---- 尾端行动区 ---- */
.page-about .ab-next {
  position: relative;
  margin-top: clamp(36px, 6vw, 72px);
  padding: clamp(24px, 4vw, 48px);
  background: var(--pitch-shadow);
  border: 1px solid var(--grid-line);
  display: grid;
  gap: clamp(12px, 2vw, 18px);
}
.page-about .ab-next::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 0;
  width: 42%;
  height: 3px;
  background: var(--neon-green);
}
.page-about .ab-next__title {
  margin: 0;
  font-size: clamp(21px, 2.8vw, 32px);
  line-height: 1.25;
  font-weight: 800;
  color: var(--cool-white);
}
.page-about .ab-next__text {
  margin: 0;
  max-width: 54ch;
  font-size: 15px;
  line-height: 1.85;
  color: var(--mist-gray);
}
.page-about .ab-next__acts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 4px;
}

/* ---- 桌面布局 ---- */
@media (min-width: 880px) {
  .page-about .ab-chapter {
    grid-template-columns: minmax(0, 3fr) minmax(0, 8fr);
    column-gap: clamp(28px, 5vw, 76px);
    align-items: start;
  }
  .page-about .ab-chapter__rail {
    grid-column: 1;
    grid-row: 1;
    position: sticky;
    top: calc(var(--header-h, 64px) + 24px);
  }
  .page-about .ab-chapter__body {
    grid-column: 2;
    grid-row: 1;
    min-width: 0;
  }
  .page-about .ab-chapter--flip {
    grid-template-columns: minmax(0, 8fr) minmax(0, 3fr);
  }
  .page-about .ab-chapter--flip .ab-chapter__rail { grid-column: 2; }
  .page-about .ab-chapter--flip .ab-chapter__body { grid-column: 1; }
}

@media (min-width: 900px) {
  .page-about .ab-hero {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
    align-items: end;
    column-gap: clamp(28px, 5vw, 72px);
  }
}

@media (min-width: 700px) {
  .page-about .ab-facts__row {
    grid-template-columns: minmax(0, 140px) minmax(0, 1fr);
    gap: clamp(16px, 3vw, 32px);
    align-items: baseline;
  }
  .page-about .ab-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .ab-timeline {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: clamp(16px, 2.4vw, 24px);
  }
}

@media (max-width: 420px) {
  .page-about .ab-tier:nth-child(2),
  .page-about .ab-tier:nth-child(3),
  .page-about .ab-tier:nth-child(4) {
    width: 100%;
  }
  .page-about .ab-chapter__rule {
    max-width: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition: none !important;
    animation: none !important;
  }
}