.page-about {
  --ab-rail: 58px;
  --ab-gap: clamp(40px, 7vw, 76px);
  --ab-sticky: 54px;
  background: var(--ink-green);
  color: var(--silver);
  font-family: var(--font-body);
  overflow-x: clip;
}

.page-about p {
  margin: 0;
}

/* ---------- 首屏 ---------- */
.ab-hero {
  position: relative;
  overflow: hidden;
  padding: clamp(20px, 4vw, 34px) 0 clamp(38px, 6vw, 68px);
  background:
    radial-gradient(120% 88% at 84% 4%, rgba(200, 255, 60, 0.11), transparent 58%),
    radial-gradient(90% 70% at 6% 96%, rgba(255, 90, 43, 0.12), transparent 62%),
    linear-gradient(168deg, var(--night-blue) 0%, var(--ink-green) 64%);
  border-bottom: 1px solid var(--line);
}

.ab-hero__mark {
  position: absolute;
  right: -3%;
  bottom: -14%;
  font-family: var(--font-mono);
  font-size: clamp(96px, 27vw, 260px);
  font-weight: 700;
  line-height: 0.78;
  letter-spacing: -0.05em;
  color: rgba(200, 255, 60, 0.055);
  pointer-events: none;
  user-select: none;
}

.ab-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: 20px;
}

.ab-hero__crumb {
  margin-bottom: 4px;
}

.ab-hero__lead {
  display: grid;
  gap: 14px;
  align-content: start;
}

.ab-hero__kicker {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--lime);
  margin: 0;
}

.ab-hero__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.025em;
  line-height: 1.04;
  font-size: clamp(32px, 8.4vw, 68px);
  color: var(--silver);
  text-wrap: balance;
}

.ab-hero__em {
  display: block;
  font-style: normal;
  color: var(--lime);
}

.ab-hero__deck {
  max-width: 58ch;
  color: rgba(233, 241, 244, 0.84);
  font-size: clamp(16px, 2.1vw, 20px);
  line-height: 1.72;
}

.ab-facts {
  margin: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line-2);
}

.ab-facts__row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding: 12px 14px;
  background: rgba(12, 24, 48, 0.62);
}

.ab-facts__row dt {
  font-size: 13px;
  color: var(--haze);
  letter-spacing: 0.02em;
}

.ab-facts__row dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 15px;
  font-variant-numeric: tabular-nums;
  color: var(--silver);
}

/* ---------- 章节带 ---------- */
.ab-toc {
  position: sticky;
  top: var(--ab-sticky);
  z-index: 20;
  background: rgba(7, 33, 27, 0.95);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.ab-toc__inner {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-top: 10px;
  padding-bottom: 10px;
}

.ab-toc__hint {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--haze);
  display: none;
}

.ab-toc__links {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

.ab-toc__links::-webkit-scrollbar {
  display: none;
}

.ab-toc__link {
  flex: 0 0 auto;
  font-size: 13px;
  padding: 6px 12px;
  border: 1px solid var(--line-2);
  color: rgba(233, 241, 244, 0.82);
  text-decoration: none;
  white-space: nowrap;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.ab-toc__link:hover,
.ab-toc__link:focus-visible {
  color: var(--lime);
  border-color: rgba(200, 255, 60, 0.5);
}

/* ---------- 时间轴 ---------- */
.ab-track {
  background: var(--ink-green);
  padding: clamp(36px, 7vw, 76px) 0 clamp(28px, 5vw, 56px);
}

.ab-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--ab-gap);
}

.ab-stage {
  display: grid;
  grid-template-columns: var(--ab-rail) minmax(0, 1fr);
  gap: 14px;
}

.ab-stage__rail {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  padding-top: 8px;
}

.ab-stage__dot {
  width: 10px;
  height: 10px;
  background: var(--lime);
  box-shadow: 0 0 0 4px rgba(200, 255, 60, 0.14);
}

.ab-stage__label {
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.5;
  letter-spacing: 0.06em;
  color: var(--haze);
}

.ab-stage__rail::after {
  content: "";
  position: absolute;
  left: 4px;
  top: 26px;
  bottom: calc(-1 * var(--ab-gap));
  width: 1px;
  background: linear-gradient(180deg, rgba(200, 255, 60, 0.44), rgba(159, 178, 196, 0.12));
}

.ab-stage:last-child .ab-stage__rail::after {
  display: none;
}

.ab-stage__body {
  display: grid;
  gap: 14px;
  align-content: start;
  min-width: 0;
}

.ab-stage--slate .ab-stage__body {
  background: linear-gradient(140deg, rgba(12, 24, 48, 0.92), rgba(18, 70, 58, 0.5));
  border: 1px solid var(--line);
  border-left: 3px solid var(--lime);
  padding: clamp(18px, 3.6vw, 30px);
}

.ab-stage__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.08;
  font-size: clamp(23px, 5.2vw, 40px);
  color: var(--silver);
}

.ab-stage__body p {
  font-size: 15px;
  line-height: 1.74;
  color: rgba(233, 241, 244, 0.8);
  max-width: 68ch;
}

.ab-stage__foot {
  font-size: 14px !important;
  color: rgba(233, 241, 244, 0.66) !important;
}

.ab-link {
  color: var(--lime);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.ab-link:hover {
  color: var(--amber);
}

.ab-stage__split {
  display: grid;
  gap: 16px;
}

.ab-stage__copy {
  display: grid;
  gap: 14px;
  align-content: start;
}

.ab-stage__fig {
  margin: 0;
}

.ab-stage__fig--wide {
  width: 100%;
}

.ab-stage__fig .media-cap {
  margin-top: 8px;
}

/* ---------- 改版前后对照 ---------- */
.ab-compare {
  display: grid;
  gap: 12px;
  margin-top: 8px;
}

.ab-compare__col {
  border: 1px solid var(--line-2);
  padding: 16px;
  background: rgba(7, 33, 27, 0.6);
  transition: transform 0.35s var(--ease), border-color 0.35s var(--ease);
}

.ab-compare__col--after {
  background: linear-gradient(140deg, rgba(18, 70, 58, 0.72), rgba(12, 24, 48, 0.6));
  border-color: rgba(200, 255, 60, 0.42);
}

.ab-compare__tag {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  margin: 0 0 10px;
  color: var(--haze);
}

.ab-compare__col--after .ab-compare__tag {
  color: var(--lime);
}

.ab-compare__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 8px;
}

.ab-compare__list li {
  position: relative;
  padding-left: 14px;
  font-size: 14px;
  line-height: 1.62;
  color: rgba(233, 241, 244, 0.78);
}

.ab-compare__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  width: 6px;
  height: 1px;
  background: var(--haze);
}

.ab-compare__col--after .ab-compare__list li::before {
  background: var(--ember);
  height: 2px;
  width: 8px;
}

.ab-compare__arrow {
  position: relative;
  justify-self: center;
  width: 2px;
  height: 34px;
  background: var(--ember);
}

.ab-compare__arrow::after {
  content: "";
  position: absolute;
  left: -4px;
  bottom: -1px;
  border-top: 9px solid var(--ember);
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
}

.ab-compare__col--before:hover {
  transform: translateY(-2px);
}

.ab-compare__col--after:hover {
  transform: translateY(-2px);
  border-color: var(--lime);
}

/* ---------- 规模数字带 ---------- */
.ab-scale {
  background: linear-gradient(120deg, var(--night-blue) 0%, #0a1f2c 55%, var(--turf-green) 130%);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  padding: clamp(34px, 6vw, 64px) 0;
}

.ab-scale__head {
  margin-bottom: clamp(20px, 3vw, 32px);
}

.ab-scale__grid {
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.ab-scale__cell {
  background: rgba(7, 33, 27, 0.72);
  padding: 18px 16px;
  display: grid;
  gap: 6px;
  align-content: start;
}

.ab-scale__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-weight: 700;
  font-size: clamp(28px, 7vw, 46px);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--lime);
}

.ab-scale__cell:nth-child(2n) .ab-scale__num {
  color: var(--ember);
}

.ab-scale__label {
  font-size: 13px;
  line-height: 1.55;
  color: rgba(233, 241, 244, 0.74);
  margin: 0;
}

/* ---------- 下一季 ---------- */
.ab-next {
  background: var(--cream);
  color: var(--brown-ink);
  padding: clamp(36px, 6vw, 72px) 0 clamp(40px, 6vw, 72px);
}

.ab-next .section-head {
  border-bottom-color: var(--paper-line);
  margin-bottom: clamp(20px, 3vw, 34px);
}

.ab-next .section-head__title {
  color: var(--ink-green);
}

.ab-next .section-head__note {
  color: rgba(26, 21, 18, 0.72);
}

.ab-next__grid {
  display: grid;
  gap: 16px;
}

.ab-next__card {
  border: 1px solid var(--paper-line);
  border-top: 3px solid var(--ember);
  background: rgba(255, 255, 255, 0.42);
  padding: 18px 16px;
  display: grid;
  gap: 8px;
  align-content: start;
}

.ab-next__idx {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--ember);
  margin: 0;
}

.ab-next__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.015em;
  font-size: clamp(19px, 3.4vw, 24px);
  line-height: 1.2;
  color: var(--ink-green);
}

.ab-next__card p {
  font-size: 14.5px;
  line-height: 1.72;
  color: rgba(26, 21, 18, 0.8);
}

.ab-next__cta {
  margin-top: clamp(24px, 4vw, 40px);
  padding-top: clamp(18px, 3vw, 28px);
  border-top: 1px solid var(--paper-line);
  display: grid;
  gap: 16px;
}

.ab-next__cta-text {
  font-family: var(--font-deck);
  font-size: clamp(17px, 2.4vw, 20px);
  line-height: 1.68;
  color: var(--ink-green);
  max-width: 46ch;
  margin: 0;
}

.ab-next__btns {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

/* ---------- 小组分工 ---------- */
.ab-groups {
  margin: 4px 0 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.ab-groups__item {
  background: rgba(12, 24, 48, 0.6);
  padding: 13px 15px;
  display: grid;
  gap: 4px;
}

.ab-groups__item dt {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 15px;
  letter-spacing: 0.01em;
  color: var(--lime);
}

.ab-groups__item dd {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.62;
  color: rgba(233, 241, 244, 0.78);
}

/* ---------- 中屏 ---------- */
@media (min-width: 720px) {
  .page-about {
    --ab-rail: 96px;
    --ab-sticky: 58px;
  }

  .ab-hero__inner {
    grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr);
    column-gap: clamp(24px, 4vw, 56px);
    row-gap: 22px;
    align-items: end;
  }

  .ab-hero__crumb {
    grid-column: 1 / -1;
  }

  .ab-hero__facts {
    align-self: end;
  }

  .ab-toc__hint {
    display: block;
  }

  .ab-stage__label {
    font-size: 12px;
  }

  .ab-stage__split {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 0.85fr);
    gap: clamp(18px, 3vw, 32px);
    align-items: start;
  }

  .ab-compare {
    grid-template-columns: minmax(0, 1fr) 46px minmax(0, 1fr);
    align-items: stretch;
    gap: 0;
  }

  .ab-compare__arrow {
    align-self: center;
    justify-self: stretch;
    width: 100%;
    height: 2px;
  }

  .ab-compare__arrow::after {
    left: auto;
    right: -1px;
    bottom: -4px;
    border-top: 5px solid transparent;
    border-bottom: 5px solid transparent;
    border-left: 10px solid var(--ember);
  }

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

  .ab-scale__cell {
    padding: 22px 20px;
  }

  .ab-next__grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 18px;
  }

  .ab-next__cta {
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: center;
    gap: 24px;
  }

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

/* ---------- 宽屏 ---------- */
@media (min-width: 1060px) {
  .ab-stage {
    grid-template-columns: 148px minmax(0, 1fr);
    gap: clamp(28px, 4vw, 64px);
  }

  .ab-stage__rail {
    position: sticky;
    top: calc(var(--ab-sticky) + 56px);
    align-self: start;
  }

  .ab-stage__rail::after {
    bottom: calc(-1 * var(--ab-gap));
  }

  .ab-stage__title {
    font-size: clamp(30px, 3.4vw, 44px);
  }

  .ab-stage__body p {
    font-size: 16px;
    line-height: 1.76;
  }

  .ab-scale__num {
    font-size: 52px;
  }
}

/* ---------- 动效偏好 ---------- */
@media (prefers-reduced-motion: reduce) {
  .ab-compare__col,
  .ab-toc__link {
    transition: none;
  }

  .ab-compare__col--before:hover,
  .ab-compare__col--after:hover {
    transform: none;
  }
}
</main>