.page-about {
  --ab-num-col: 132px;
  --ab-gap: 48px;
  display: block;
  background: var(--c-void);
}

/* ---------------- Hero ---------------- */
.page-about .ab-hero {
  padding: 20px 0 10px;
}

.page-about .ab-hero__frame {
  position: relative;
  border: 2px solid var(--c-lime);
  background: var(--grad-band);
  box-shadow: var(--shadow-hard-lg);
  padding: 36px 20px 30px;
}

.page-about .ab-hero__frame::before,
.page-about .ab-hero__frame::after {
  content: "";
  position: absolute;
  width: 44px;
  height: 44px;
  pointer-events: none;
}

.page-about .ab-hero__frame::before {
  top: 8px;
  right: 8px;
  border-top: 2px solid var(--c-lime);
  border-right: 2px solid var(--c-lime);
}

.page-about .ab-hero__frame::after {
  bottom: 8px;
  left: 8px;
  border-bottom: 2px solid var(--c-lime);
  border-left: 2px solid var(--c-lime);
}

.page-about .ab-hero__tick {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 8px;
  opacity: .45;
  background-image: repeating-linear-gradient(90deg, var(--c-lime) 0 1px, transparent 1px 18px);
}

.page-about .ab-hero__kicker {
  margin: 0 0 14px;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: .22em;
  color: var(--c-lime);
  text-transform: uppercase;
}

.page-about .ab-hero__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(40px, 11vw, 84px);
  line-height: .94;
  letter-spacing: .02em;
  color: var(--c-paper);
}

.page-about .ab-hero__sub {
  margin: 14px 0 0;
  font-family: var(--font-num);
  font-size: 13px;
  letter-spacing: .16em;
  color: var(--c-silver);
}

.page-about .ab-hero__lead {
  margin: 24px 0 0;
  max-width: 34em;
  color: var(--c-silver);
  line-height: 1.75;
}

.page-about .ab-hero__stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(128px, 1fr));
  gap: 2px;
  margin-top: 30px;
  border: 2px solid var(--c-line-strong);
  background: var(--c-line-strong);
}

.page-about .ab-hero__stat {
  background: var(--c-panel);
  padding: 15px 14px 17px;
}

.page-about .ab-hero__stat-num {
  display: block;
  font-family: var(--font-num);
  font-size: 30px;
  font-weight: 700;
  line-height: 1;
  color: var(--c-lime);
  font-variant-numeric: tabular-nums;
}

.page-about .ab-hero__stat-label {
  display: block;
  margin-top: 9px;
  font-size: 12px;
  letter-spacing: .12em;
  color: var(--c-silver-dim);
}

/* ---------------- Chapter shell ---------------- */
.page-about .ab-ch {
  padding: 44px 0 40px;
  border-top: 1px solid var(--c-line);
}

.page-about .ab-ch__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

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

.page-about .ab-ch__no {
  display: block;
  font-family: var(--font-num);
  font-size: 44px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -.03em;
  color: var(--c-silver-dim);
  font-variant-numeric: tabular-nums;
  transition: color var(--dur) ease;
}

.page-about .ab-ch__no.is-in {
  color: var(--c-lime);
}

.page-about .ab-ch__note {
  display: block;
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--c-silver-dim);
}

.page-about .ab-ch__title {
  margin: 0 0 18px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(24px, 5.4vw, 34px);
  line-height: 1.2;
  letter-spacing: .02em;
  color: var(--c-paper);
}

.page-about .ab-ch__body p {
  margin: 0 0 16px;
  color: var(--c-silver);
  line-height: 1.75;
}

.page-about .ab-ch__body > p,
.page-about .ab-ch__body .ab-split__text p {
  max-width: 36em;
}

.page-about .ab-ch__tail {
  margin-top: 22px;
  padding-top: 18px;
  border-top: 1px solid var(--c-line);
  font-size: 13.5px;
  color: var(--c-silver-dim);
}

/* ---------------- Media block ---------------- */
.page-about .ab-media {
  position: relative;
  margin: 0;
  border: 2px solid var(--c-line-strong);
  background: var(--c-panel);
  box-shadow: var(--shadow-hard);
  overflow: hidden;
}

.page-about .ab-media img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

.page-about .ab-media figcaption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 26px 12px 9px;
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--c-silver);
  background: linear-gradient(180deg, transparent, var(--c-void));
}

/* ---------------- Chapter 01 split ---------------- */
.page-about .ab-split {
  display: grid;
  gap: 24px;
}

.page-about .ab-split__figure {
  margin: 0;
}

/* ---------------- Chapter 02 teams ---------------- */
.page-about .ab-teams {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2px;
  margin-top: 24px;
  border: 2px solid var(--c-line-strong);
  background: var(--c-line-strong);
}

.page-about .ab-team {
  background: var(--c-panel);
  padding: 24px 18px 22px;
  transition: background var(--dur) ease, box-shadow var(--dur) ease;
}

.page-about .ab-team:hover,
.page-about .ab-team:focus-within {
  background: var(--c-panel-2);
  box-shadow: inset 0 -4px 0 var(--c-lime);
}

.page-about .ab-team__count {
  display: inline-block;
  font-family: var(--font-num);
  font-size: 34px;
  font-weight: 700;
  line-height: 1;
  color: var(--c-lime);
  font-variant-numeric: tabular-nums;
}

.page-about .ab-team__unit {
  margin-left: 6px;
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--c-silver-dim);
}

.page-about .ab-team__name {
  margin: 12px 0 6px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 20px;
  letter-spacing: .04em;
  color: var(--c-paper);
}

.page-about .ab-team__role {
  margin: 0 0 16px;
  font-size: 13px;
  letter-spacing: .06em;
  color: var(--c-orange);
}

.page-about .ab-team__fields {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--c-line);
}

.page-about .ab-team__fields li {
  position: relative;
  padding: 9px 0 9px 16px;
  font-size: 13.5px;
  line-height: 1.62;
  color: var(--c-silver-dim);
  border-bottom: 1px solid var(--c-line);
  transition: color var(--dur) ease;
}

.page-about .ab-team__fields li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 17px;
  width: 7px;
  height: 7px;
  background: var(--c-silver-dim);
  transition: background var(--dur) ease;
}

.page-about .ab-team:hover .ab-team__fields li,
.page-about .ab-team:focus-within .ab-team__fields li {
  color: var(--c-silver);
}

.page-about .ab-team:hover .ab-team__fields li::before,
.page-about .ab-team:focus-within .ab-team__fields li::before {
  background: var(--c-lime);
}

/* ---------------- Chapter 03 pipeline ---------------- */
.page-about .ab-pipe-figure {
  margin: 24px 0 0;
}

.page-about .ab-pipe {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 2px;
  border: 2px solid var(--c-line-strong);
  background: var(--c-line-strong);
}

.page-about .ab-ch__body .ab-pipe__step {
  background: var(--c-panel);
  padding: 22px 18px 20px;
}

.page-about .ab-pipe__idx {
  display: inline-block;
  padding: 3px 9px;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--c-void);
  background: var(--c-lime);
}

.page-about .ab-pipe__step h3 {
  margin: 14px 0 10px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: .04em;
  color: var(--c-paper);
}

.page-about .ab-ch__body .ab-pipe__step p {
  margin: 0 0 12px;
  font-size: 13.5px;
  line-height: 1.7;
}

.page-about .ab-ch__body .ab-pipe__check {
  margin: 0;
  padding-top: 12px;
  font-size: 12.5px;
  color: var(--c-silver-dim);
  border-top: 1px dashed var(--c-line);
}

/* ---------------- Chapter 04 version scale ---------------- */
.page-about .ab-scale {
  margin-top: 26px;
  border: 2px solid var(--c-line-strong);
  background: var(--c-panel);
  overflow-x: auto;
  overflow-y: hidden;
  scrollbar-width: thin;
  scrollbar-color: var(--c-lime-dim) var(--c-panel);
  -webkit-overflow-scrolling: touch;
}

.page-about .ab-scale:focus-visible {
  outline: 2px solid var(--c-lime);
  outline-offset: 3px;
}

.page-about .ab-scale__track {
  position: relative;
  display: flex;
  margin: 0;
  padding: 0;
  list-style: none;
  min-width: max-content;
}

.page-about .ab-scale__track::before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 40px;
  height: 2px;
  background: var(--c-line-strong);
}

.page-about .ab-scale__node {
  position: relative;
  flex: 0 0 auto;
  width: 180px;
  padding: 66px 16px 22px;
  border-right: 1px dashed var(--c-line);
}

.page-about .ab-scale__node:last-child {
  border-right: 0;
}

.page-about .ab-scale__ver {
  position: absolute;
  top: 14px;
  left: 16px;
  font-family: var(--font-num);
  font-size: 16px;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--c-paper);
  font-variant-numeric: tabular-nums;
}

.page-about .ab-scale__dot {
  position: absolute;
  top: 33px;
  left: 16px;
  width: 14px;
  height: 14px;
  background: var(--c-lime);
  border: 2px solid var(--c-void);
}

.page-about .ab-scale__node--key .ab-scale__dot {
  background: var(--c-orange);
}

.page-about .ab-scale__node--key .ab-scale__ver {
  color: var(--c-orange);
}

.page-about .ab-ch__body .ab-scale__desc {
  margin: 0;
  font-size: 13px;
  line-height: 1.65;
  color: var(--c-silver-dim);
}

.page-about .ab-archive {
  display: grid;
  gap: 24px;
  margin-top: 28px;
}

.page-about .ab-archive__figure {
  margin: 0;
}

.page-about .ab-ch__body .ab-archive__text p {
  font-size: 14.5px;
}

/* ---------------- Chapter 05 boundary ---------------- */
.page-about .ab-rules {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2px;
  margin-top: 22px;
  border: 2px solid var(--c-line-strong);
  background: var(--c-line-strong);
}

.page-about .ab-ch__body .ab-rule {
  background: var(--c-panel);
  padding: 20px 18px 22px;
}

.page-about .ab-rule h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: .04em;
  color: var(--c-lime);
}

.page-about .ab-ch__body .ab-rule p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.7;
}

.page-about .ab-feedback {
  margin-top: 26px;
  padding: 22px 20px 16px;
  border: 2px solid var(--c-lime);
  background: var(--c-panel);
  box-shadow: var(--shadow-hard);
}

.page-about .ab-feedback__lead {
  margin: 0 0 14px;
  font-size: 13.5px;
  color: var(--c-silver);
}

.page-about .ab-feedback__item {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 14px;
  padding: 11px 0;
  border-top: 1px solid var(--c-line);
}

.page-about .ab-feedback__key {
  flex: 0 0 auto;
  min-width: 88px;
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--c-silver-dim);
  padding-top: 2px;
}

.page-about .ab-feedback__val {
  flex: 1 1 auto;
  min-width: 0;
  font-family: var(--font-num);
  font-size: 14px;
  color: var(--c-paper);
  word-break: break-word;
}

.page-about .ab-index {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2px;
  margin-top: 30px;
  border: 2px solid var(--c-line-strong);
  background: var(--c-line-strong);
}

.page-about .ab-index__link {
  position: relative;
  display: block;
  padding: 20px 18px 28px;
  background: var(--c-panel);
  text-decoration: none;
  transition: background var(--dur) ease;
}

.page-about .ab-index__link::after {
  content: "";
  position: absolute;
  left: 18px;
  right: 18px;
  bottom: 14px;
  height: 2px;
  background: var(--c-lime);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) ease;
}

.page-about .ab-index__link:hover,
.page-about .ab-index__link:focus-visible {
  background: var(--c-panel-2);
}

.page-about .ab-index__link:hover::after,
.page-about .ab-index__link:focus-visible::after {
  transform: scaleX(1);
}

.page-about .ab-index__label {
  display: block;
  font-family: var(--font-num);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--c-lime-dim);
}

.page-about .ab-index__title {
  display: block;
  margin-top: 8px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  letter-spacing: .04em;
  color: var(--c-paper);
}

.page-about .ab-index__desc {
  display: block;
  margin-top: 6px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--c-silver-dim);
}

/* ---------------- Responsive ---------------- */
@media (min-width: 700px) {
  .page-about .ab-hero__frame {
    padding: 46px 34px 38px;
  }

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

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

@media (min-width: 880px) {
  .page-about .ab-ch {
    padding: 56px 0 50px;
  }

  .page-about .ab-ch__grid {
    grid-template-columns: var(--ab-num-col) minmax(0, 1fr);
    gap: var(--ab-gap);
  }

  .page-about .ab-ch__rail {
    display: block;
    position: sticky;
    top: 92px;
    align-self: start;
  }

  .page-about .ab-ch__no {
    font-size: 68px;
  }

  .page-about .ab-ch__note {
    margin-top: 18px;
    writing-mode: vertical-rl;
    letter-spacing: .3em;
    line-height: 1;
  }

  .page-about .ab-split {
    grid-template-columns: minmax(0, 1fr) minmax(0, 300px);
    gap: 34px;
    align-items: start;
  }

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

  .page-about .ab-archive {
    grid-template-columns: minmax(0, 250px) minmax(0, 1fr);
    gap: 36px;
    align-items: start;
  }

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

@media (min-width: 1180px) {
  .page-about .ab-hero__frame {
    padding: 56px 48px 44px;
  }

  .page-about .ab-scale__node {
    width: 196px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .ab-ch__no,
  .page-about .ab-team,
  .page-about .ab-team__fields li,
  .page-about .ab-team__fields li::before,
  .page-about .ab-index__link,
  .page-about .ab-index__link::after {
    transition: none;
  }
}