.page-about {
  --ab-line: #22304A;
  --ab-block-gap: clamp(64px, 7vw, 96px);
  color: var(--c-mist);
  background:
    linear-gradient(180deg,
      var(--c-ink) 0%,
      var(--c-ink) 16%,
      var(--c-hull) 42%,
      var(--c-hull) 58%,
      var(--c-ink) 100%);
}

/* ---------- breadcrumb ---------- */
.page-about .breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--c-lead);
  margin-bottom: clamp(24px, 4vw, 40px);
}
.page-about .breadcrumb a {
  color: var(--c-lead);
  text-decoration: none;
  transition: color var(--dur-micro) var(--ease);
}
.page-about .breadcrumb a:hover { color: var(--c-paper); }
.page-about .breadcrumb .breadcrumb-sep { color: var(--ab-line); }

/* ---------- hero ---------- */
.page-about .about-hero {
  padding: clamp(48px, 7vw, 96px) 0 clamp(40px, 5vw, 64px);
  border-bottom: 1px solid var(--ab-line);
}
.page-about .hero-head { max-width: 900px; }
.page-about .hero-head .display-xl {
  margin: 16px 0 24px;
  color: var(--c-paper);
}
.page-about .hero-head .lede {
  max-width: 46ch;
  margin: 0;
  font-size: 17px;
  line-height: 1.85;
  color: var(--c-mist);
}

/* ---------- hero timeline ---------- */
.page-about .hero-timeline {
  margin-top: clamp(40px, 6vw, 72px);
  padding: clamp(18px, 2.4vw, 26px) clamp(16px, 2.4vw, 28px) clamp(20px, 2.6vw, 30px);
  border: 1px solid var(--ab-line);
  background: rgba(19, 28, 43, 0.62);
}
.page-about .htl-head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 8px 20px;
  margin-bottom: clamp(22px, 3vw, 34px);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-lead);
}
.page-about .htl-head .htl-label { color: var(--c-mist); }
.page-about .htl-track {
  position: relative;
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 2px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .htl-track::before {
  content: "";
  position: absolute;
  top: 5px;
  left: 6px;
  right: 6px;
  height: 1px;
  background: var(--ab-line);
}
.page-about .htl-node {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  cursor: default;
}
.page-about .htl-tick {
  position: relative;
  z-index: 1;
  display: block;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--c-hull);
  border: 1px solid var(--ab-line);
}
.page-about .htl-node.is-done .htl-tick {
  background: var(--c-cyan);
  border-color: var(--c-cyan);
}
.page-about .htl-node.is-current .htl-tick {
  background: var(--c-brand);
  border-color: var(--c-brand);
  box-shadow: 0 0 0 4px rgba(30, 94, 255, 0.2);
}
.page-about .htl-node.is-next .htl-tick {
  background: transparent;
  border-color: var(--c-lead);
}
.page-about .htl-num {
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--c-lead);
}
.page-about .htl-node.is-done .htl-num { color: var(--c-cyan); }
.page-about .htl-node.is-current .htl-num { color: var(--c-paper); }
.page-about .htl-node.is-next .htl-num { color: var(--c-lead); }

.page-about .htl-node::after {
  content: attr(data-tip);
  position: absolute;
  top: calc(100% + 10px);
  left: 50%;
  transform: translateX(-50%);
  z-index: 4;
  padding: 6px 10px;
  border: 1px solid var(--ab-line);
  background: var(--c-ink);
  color: var(--c-mist);
  font-size: 11px;
  line-height: 1.4;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-micro) var(--ease);
}
.page-about .htl-node:hover::after,
.page-about .htl-node:focus-within::after { opacity: 1; }

@media (prefers-reduced-motion: no-preference) {
  .page-about .htl-node.is-current .htl-tick {
    animation: about-breathe 2.4s ease-in-out infinite;
  }
  @keyframes about-breathe {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.12); }
  }
}

/* ---------- .page-about layout ---------- */
.page-about .about-body {
  padding: clamp(56px, 7vw, 96px) 0 clamp(88px, 9vw, 136px);
}
.page-about .about-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 56px;
}
.page-about .about-content {
  min-width: 0;
}
.page-about .about-section {
  padding-bottom: var(--ab-block-gap);
  margin-bottom: var(--ab-block-gap);
  border-bottom: 1px solid var(--ab-line);
}
.page-about .about-section:last-child {
  padding-bottom: 0;
  margin-bottom: 0;
  border-bottom: 0;
}
.page-about .about-section .section-title {
  margin: 10px 0 22px;
  color: var(--c-paper);
}
.page-about .about-section p {
  max-width: 42em;
  margin: 0 0 18px;
  font-size: 16px;
  line-height: 1.85;
  color: var(--c-mist);
}
.page-about .about-section p:last-child { margin-bottom: 0; }

/* ---------- principle block ---------- */
.page-about .principle {
  margin: 28px 0;
  padding: 22px 24px;
  border-left: 3px solid var(--c-cyan);
  background: rgba(43, 227, 208, 0.06);
}
.page-about .principle p {
  max-width: 40em;
  margin: 0;
  font-size: 18px;
  line-height: 1.8;
  color: var(--c-paper);
}

/* ---------- boundary list ---------- */
.page-about .boundary-list {
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 14px;
}
.page-about .boundary-list li {
  display: grid;
  grid-template-columns: 14px minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  font-size: 15px;
  line-height: 1.75;
  color: var(--c-mist);
}
.page-about .boundary-mark {
  display: block;
  width: 9px;
  height: 9px;
  margin-top: 9px;
  background: var(--c-cyan);
}

/* ---------- figure ---------- */
.page-about .figure {
  margin: 32px 0 0;
}
.page-about .figure .figure-frame {
  border: 1px solid var(--ab-line);
  background: var(--c-hull);
  overflow: hidden;
}
.page-about .figure .figure-frame img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}
.page-about .figure .figure-caption {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--c-lead);
}
.page-about .figure .figure-caption-tag {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-paper);
  padding: 2px 8px;
  border: 1px solid var(--ab-line);
  background: var(--c-ink-soft);
}

/* ---------- cadence list ---------- */
.page-about .cadence-list {
  margin: 30px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--ab-line);
}
.page-about .cadence-item {
  display: grid;
  grid-template-columns: 18px minmax(0, 1fr);
  gap: 16px;
  align-items: start;
  padding: 20px 0;
  border-bottom: 1px solid var(--ab-line);
}
.page-about .cadence-dot {
  display: block;
  width: 10px;
  height: 10px;
  margin-top: 7px;
  background: var(--c-hull);
  border: 1px solid var(--ab-line);
}
.page-about .cadence-item.is-done .cadence-dot {
  background: var(--c-cyan);
  border-color: var(--c-cyan);
}
.page-about .cadence-item.is-current .cadence-dot {
  background: var(--c-brand);
  border-color: var(--c-brand);
}
.page-about .cadence-item.is-next .cadence-dot {
  background: transparent;
  border-color: var(--c-lead);
}
.page-about .cadence-title {
  margin: 0 0 8px;
  font-size: 15px;
  font-weight: 600;
  color: var(--c-paper);
}
.page-about .cadence-title .mono {
  margin-left: 10px;
  font-size: 12px;
  font-weight: 500;
  color: var(--c-lead);
}
.page-about .cadence-item.is-done .cadence-title .mono { color: var(--c-cyan); }
.page-about .cadence-item.is-current .cadence-title .mono { color: var(--c-brand); }
.page-about .cadence-text {
  margin: 0 !important;
  max-width: 44em;
  font-size: 15px;
  line-height: 1.8;
}

@media (prefers-reduced-motion: no-preference) {
  .page-about .cadence-item.is-current .cadence-dot {
    animation: about-breathe 2.4s ease-in-out infinite;
  }
}

/* ---------- team chart ---------- */
.page-about .team-chart {
  margin-top: 30px;
  padding: 22px 20px 20px;
  border: 1px solid var(--ab-line);
  background: rgba(19, 28, 43, 0.55);
}
.page-about .team-bar {
  display: flex;
  gap: 2px;
  height: 16px;
}
.page-about .team-bar > span { height: 100%; }
.page-about .team-bar .tb-eng { flex: 26 1 0; background: var(--c-brand); }
.page-about .team-bar .tb-content { flex: 12 1 0; background: var(--c-cyan); }
.page-about .team-bar .tb-pd { flex: 9 1 0; background: var(--c-mist); }
.page-about .team-bar .tb-cs { flex: 11 1 0; background: var(--c-amber); }

.page-about .team-legend {
  margin: 22px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 10px;
}
.page-about .team-row {
  display: grid;
  grid-template-columns: 12px minmax(0, 1fr) auto;
  align-items: center;
  gap: 12px;
  padding-bottom: 8px;
  border-bottom: 1px dashed var(--ab-line);
  font-size: 14px;
}
.page-about .team-row:last-child { border-bottom: 0; padding-bottom: 0; }
.page-about .team-swatch {
  display: block;
  width: 10px;
  height: 10px;
}
.page-about .team-swatch.tb-eng { background: var(--c-brand); }
.page-about .team-swatch.tb-content { background: var(--c-cyan); }
.page-about .team-swatch.tb-pd { background: var(--c-mist); }
.page-about .team-swatch.tb-cs { background: var(--c-amber); }
.page-about .team-name { color: var(--c-mist); }
.page-about .team-count { color: var(--c-paper); }

/* ---------- ecosystem list ---------- */
.page-about .ecosystem-list {
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 1px;
  border: 1px solid var(--ab-line);
  background: var(--ab-line);
}
.page-about .ecosystem-list li {
  background: var(--c-ink);
  padding: 18px 20px;
}
.page-about .eco-title {
  margin: 0 0 6px !important;
  font-size: 15px;
  font-weight: 600;
  color: var(--c-paper);
}
.page-about .eco-text {
  margin: 0 !important;
  font-size: 14px;
  line-height: 1.8;
  color: var(--c-mist);
}

/* ---------- section tail ---------- */
.page-about .section-tail {
  margin-top: 30px !important;
  padding-top: 20px;
  border-top: 1px dashed var(--ab-line);
  font-size: 14px !important;
  line-height: 1.85;
  color: var(--c-lead) !important;
}
.page-about .section-tail a {
  color: var(--c-paper);
  text-decoration: none;
  border-bottom: 1px solid var(--c-brand);
  padding-bottom: 1px;
  transition: color var(--dur-micro) var(--ease), border-color var(--dur-micro) var(--ease);
}
.page-about .section-tail a:hover {
  color: var(--c-brand);
  border-color: var(--c-cyan);
}

/* ---------- side rail ---------- */
.page-about .about-side {
  display: grid;
  gap: 28px;
  align-content: start;
}
.page-about .side-block {
  padding-top: 18px;
  border-top: 1px solid var(--ab-line);
}
.page-about .side-title {
  margin: 0 0 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--c-lead);
}
.page-about .side-toc {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 2px;
}
.page-about .side-toc a {
  display: block;
  padding: 8px 10px;
  border-left: 2px solid transparent;
  color: var(--c-mist);
  font-size: 14px;
  text-decoration: none;
  transition: color var(--dur-micro) var(--ease), border-color var(--dur-micro) var(--ease), background var(--dur-micro) var(--ease);
}
.page-about .side-toc a:hover {
  color: var(--c-paper);
  border-left-color: var(--c-brand);
}
.page-about .side-toc a:focus-visible {
  outline: 2px solid var(--c-cyan);
  outline-offset: 2px;
}
.page-about .side-facts {
  margin: 0;
  display: grid;
  gap: 10px;
}
.page-about .side-fact {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding-bottom: 8px;
  border-bottom: 1px dashed var(--ab-line);
  font-size: 13px;
}
.page-about .side-fact:last-child { border-bottom: 0; padding-bottom: 0; }
.page-about .side-fact dt { color: var(--c-lead); }
.page-about .side-fact dd {
  margin: 0;
  color: var(--c-paper);
  font-size: 13px;
}

/* ---------- responsive ---------- */
@media (max-width: 640px) {
  .page-about .htl-track {
    grid-template-columns: repeat(5, 1fr);
    row-gap: 22px;
  }
  .page-about .htl-track::before { display: none; }
  .page-about .htl-node::after { display: none; }
  .page-about .hero-head .display-xl { font-size: clamp(40px, 12vw, 64px); }
  .page-about .principle { padding: 18px 16px; }
  .page-about .principle p { font-size: 16px; }
  .page-about .team-chart { padding: 16px 14px; }
  .page-about .ecosystem-list li { padding: 16px 16px; }
}

@media (min-width: 900px) {
  .page-about .about-grid {
    grid-template-columns: minmax(0, 7fr) minmax(232px, 3fr);
    gap: clamp(48px, 6vw, 88px);
    align-items: start;
  }
  .page-about .about-side {
    position: sticky;
    top: 120px;
  }
}

@media (min-width: 1200px) {
  .page-about .hero-head { max-width: 1020px; }
  .page-about .about-section p { font-size: 17px; }
}
<<<END>>>