.page-about {
  background: var(--color-bg);
  color: var(--color-text);
}

.page-about .ab-hero {
  position: relative;
  padding: var(--space-6) 0 var(--space-7);
  overflow: hidden;
}

.page-about .ab-hero::before {
  content: "";
  position: absolute;
  top: -140px;
  right: -140px;
  width: 360px;
  height: 360px;
  background: radial-gradient(circle, rgba(255, 107, 0, 0.28), rgba(255, 107, 0, 0) 70%);
  pointer-events: none;
}

.page-about .ab-hero__grid {
  display: grid;
  gap: var(--space-6);
  align-items: center;
}

.page-about .ab-hero__copy {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
  align-items: flex-start;
}

.page-about .ab-hero__lead {
  color: var(--color-text-secondary);
  font-size: 1.05rem;
  line-height: 1.75;
  max-width: 58ch;
  margin: 0;
}

.page-about .ab-hero__stats {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  margin-top: var(--space-2);
}

.page-about .ab-hero__stat {
  border-left: 2px solid var(--color-cyan);
  padding: var(--space-1) var(--space-3);
}

.page-about .ab-hero__stat .data-number {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-orange);
  display: block;
  line-height: 1.1;
}

.page-about .ab-hero__stat-label {
  color: var(--color-text-secondary);
  font-size: 0.8rem;
  letter-spacing: 0.04em;
}

.page-about .ab-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-top: var(--space-2);
}

.page-about .ab-hero__visual {
  position: relative;
  border: 1px solid var(--color-line);
  background: var(--color-panel);
}

.page-about .ab-hero__img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 11 / 8;
  object-fit: cover;
}

.page-about .ab-hero__svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.page-about .ab-hero__svg text,
.page-about .ab-data__chart text {
  font-family: var(--font-mono), "PingFang SC", "Microsoft YaHei", sans-serif;
}

.page-about .ab-hero__badge {
  position: absolute;
  right: var(--space-4);
  bottom: var(--space-4);
  background: rgba(11, 30, 58, 0.88);
  border: 1px solid var(--color-orange);
  color: var(--color-orange);
  padding: var(--space-2) var(--space-3);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  letter-spacing: 0.05em;
}

.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  align-items: center;
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.page-about .breadcrumb a {
  color: var(--color-cyan);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition-fast) ease;
}

.page-about .breadcrumb a:hover {
  border-bottom-color: var(--color-cyan);
}

.page-about .breadcrumb [aria-current="page"] {
  color: var(--color-text);
}

.page-about .ab-section-head {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  margin-bottom: var(--space-5);
}

.page-about .ab-section-head h2 {
  font-family: var(--font-heading);
  font-style: italic;
  font-weight: 800;
  font-size: clamp(1.6rem, 2.4vw, 2.5rem);
  letter-spacing: -0.02em;
  margin: 0;
}

.page-about .ab-section-head__desc {
  color: var(--color-text-secondary);
  margin: 0;
  max-width: 64ch;
  line-height: 1.7;
}

.page-about .ab-milestones {
  padding: var(--space-7) 0;
  border-top: 1px solid var(--color-line);
}

.page-about .ab-milestones .filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-5);
}

.page-about .filter-btn {
  padding: var(--space-2) var(--space-3);
  background: var(--color-panel);
  border: 1px solid var(--color-line);
  color: var(--color-text-secondary);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  cursor: pointer;
  transition: background var(--transition-fast) ease, color var(--transition-fast) ease, border-color var(--transition-fast) ease;
}

.page-about .filter-btn.is-active {
  background: var(--color-orange);
  color: var(--color-bg);
  border-color: var(--color-orange);
}

.page-about .ab-milestones__banner {
  margin: 0 0 var(--space-5);
  border: 1px solid var(--color-line);
  background: var(--color-panel);
}

.page-about .ab-milestones__banner img {
  width: 100%;
  height: auto;
  display: block;
  object-fit: cover;
  max-height: 400px;
}

.page-about .ab-timeline__layout {
  display: grid;
  gap: var(--space-5);
  margin-top: var(--space-5);
}

.page-about .ab-timeline__index {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.page-about .ab-timeline__index-item {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-line);
  padding: var(--space-1) var(--space-2);
  background: var(--color-panel);
}

.page-about .ab-timeline__cards {
  display: grid;
  gap: var(--space-5);
  align-self: start;
}

.page-about .ab-timeline__card {
  position: relative;
  background: var(--color-panel);
  border-left: 3px solid var(--color-cyan);
  padding: var(--space-5);
  transition: transform var(--transition-fast) ease, background var(--transition-fast) ease;
}

.page-about .ab-timeline__card:hover {
  transform: translateY(-2px);
  background: var(--color-panel-hover);
}

.page-about .ab-timeline__card--highlight {
  border-left-color: var(--color-orange);
}

.page-about .ab-timeline__year {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  line-height: 1;
  color: var(--color-orange);
  display: block;
}

.page-about .ab-timeline__body h3 {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  margin: var(--space-2) 0 var(--space-2);
}

.page-about .ab-timeline__body p {
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin: 0;
}

.page-about .ab-milestone__details {
  margin-top: var(--space-3);
  padding-top: var(--space-2);
  border-top: 1px solid var(--color-line);
}

.page-about .ab-milestone__details summary {
  cursor: pointer;
  color: var(--color-cyan);
  font-weight: 600;
  list-style: none;
}

.page-about .ab-milestone__details summary::-webkit-details-marker {
  display: none;
}

.page-about .ab-milestone__details summary::after {
  content: "＋";
  margin-left: var(--space-2);
  color: var(--color-orange);
  font-family: var(--font-mono);
}

.page-about .ab-milestone__details[open] summary::after {
  content: "－";
}

.page-about .ab-milestone__list {
  margin: var(--space-2) 0 0;
  padding-left: var(--space-4);
  color: var(--color-text-secondary);
  font-size: 0.9rem;
}

.page-about .ab-milestone__list li {
  margin-bottom: var(--space-1);
}

.page-about .ab-data {
  padding: var(--space-7) 0;
  border-top: 1px solid var(--color-line);
}

.page-about .ab-data__grid {
  display: grid;
  gap: var(--space-4);
  margin-bottom: var(--space-5);
}

.page-about .ab-data__stat {
  background: var(--color-panel);
  border: 1px solid var(--color-line);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.page-about .ab-data__stat h3 {
  font-family: var(--font-mono);
  font-size: 2.2rem;
  color: var(--color-orange);
  margin: 0;
  line-height: 1.1;
}

.page-about .ab-data__stat p {
  margin: 0;
  color: var(--color-text-secondary);
}

.page-about .ab-data__stat--feature {
  background: linear-gradient(135deg, var(--color-panel) 0%, var(--color-panel-hover) 100%);
  border-left: 3px solid var(--color-orange);
}

.page-about .ab-data__content {
  display: grid;
  gap: var(--space-5);
}

.page-about .ab-data__chart {
  border: 1px solid var(--color-line);
  background: var(--color-panel);
}

.page-about .ab-data__chart svg {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .ab-data__feature h3 {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  margin: 0 0 var(--space-2);
}

.page-about .ab-data__feature p {
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin: 0;
}

.page-about .ab-data__tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  list-style: none;
  padding: 0;
  margin: var(--space-3) 0 0;
}

.page-about .ab-data__tag {
  border: 1px solid var(--color-line);
  padding: var(--space-1) var(--space-2);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  background: var(--color-bg);
}

.page-about .ab-architecture {
  padding: var(--space-7) 0;
  border-top: 1px solid var(--color-line);
}

.page-about .ab-architecture__grid {
  display: grid;
  gap: var(--space-4);
}

.page-about .ab-arch-card {
  position: relative;
  background: var(--color-panel);
  border: 1px solid var(--color-line);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  transition: transform var(--transition-fast) ease, border-color var(--transition-fast) ease;
}

.page-about .ab-arch-card:hover {
  transform: translateY(-2px);
  border-color: var(--color-cyan);
}

.page-about .ab-arch-card__index {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-cyan);
  letter-spacing: 0.08em;
}

.page-about .ab-arch-card h3 {
  font-family: var(--font-heading);
  font-size: 1.2rem;
  margin: 0;
}

.page-about .ab-arch-card p {
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin: 0;
  font-size: 0.95rem;
}

.page-about .ab-arch-card a {
  color: var(--color-orange);
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  margin-top: auto;
}

.page-about .ab-arch-card a::after {
  content: "→";
  margin-left: var(--space-1);
  color: var(--color-cyan);
}

.page-about .ab-architecture__media {
  margin-top: var(--space-5);
  border: 1px solid var(--color-line);
  background: var(--color-panel);
}

.page-about .ab-architecture__media img {
  width: 100%;
  height: auto;
  aspect-ratio: 8 / 5;
  object-fit: cover;
  display: block;
}

.page-about .ab-compliance {
  padding: var(--space-7) 0;
  border-top: 1px solid var(--color-cyan);
}

.page-about .ab-compliance__grid {
  display: grid;
  gap: var(--space-5);
}

.page-about .ab-compliance__block {
  background: var(--color-panel);
  border-left: 3px solid var(--color-cyan);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.page-about .ab-compliance__block h3 {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  margin: 0;
}

.page-about .ab-compliance__block p,
.page-about .ab-compliance__block li {
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin: 0;
}

.page-about .ab-compliance__block ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.page-about .ab-compliance__block li {
  padding: var(--space-1) 0;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  border-bottom: 1px dashed var(--color-line);
}

.page-about .ab-compliance__block .btn {
  align-self: flex-start;
  margin-top: var(--space-2);
}

@media (min-width: 900px) {
  .page-about .ab-hero {
    padding: var(--space-8) 0;
  }

  .page-about .ab-hero__grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
    gap: var(--space-7);
  }

  .page-about .ab-hero__badge {
    bottom: var(--space-5);
    right: var(--space-5);
  }

  .page-about .ab-timeline__layout {
    grid-template-columns: 160px minmax(0, 1fr);
    gap: var(--space-5);
  }

  .page-about .ab-timeline__index {
    position: sticky;
    top: calc(var(--command-h) + var(--space-5));
    flex-direction: column;
    align-self: start;
  }

  .page-about .ab-data__grid {
    grid-template-columns: repeat(3, 1fr);
    margin-bottom: var(--space-6);
  }

  .page-about .ab-data__content {
    grid-template-columns: 1.1fr 0.9fr;
    align-items: center;
  }

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

  .page-about .ab-arch-card:nth-child(1) {
    grid-column: span 2;
  }

  .page-about .ab-arch-card:nth-child(4) {
    grid-column: span 2;
  }

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