.page-about {
  background: var(--color-bg);
  color: var(--color-text);
  padding-bottom: var(--space-xl);
}

.page-about .about-hero {
  position: relative;
  padding: 40px 0 48px;
  border-bottom: 1px solid var(--color-border);
  overflow: hidden;
}

.page-about .breadcrumb {
  margin-bottom: 32px;
}

.page-about .hero-inner {
  position: relative;
  z-index: 2;
  max-width: 720px;
}

.page-about .hero-inner h1 {
  font-family: var(--font-headline);
  font-size: clamp(2rem, 5vw, 3.75rem);
  font-weight: 300;
  line-height: 1.15;
  margin: 16px 0 24px;
  letter-spacing: 0.02em;
}

.page-about .h1-sub {
  display: block;
  color: var(--color-primary);
}

.page-about .hero-desc {
  font-size: 1.05rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
  max-width: 640px;
  margin-bottom: 32px;
}

.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.page-about .hero-bg-line {
  position: absolute;
  right: -80px;
  top: 0;
  width: 70%;
  height: 220px;
  opacity: 0.5;
  pointer-events: none;
}

.page-about .archive-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
  margin-top: 40px;
}

.page-about .archive-index {
  border-left: 2px solid var(--color-border);
  padding-left: 24px;
}

.page-about .index-caption {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--color-text-secondary);
  margin-bottom: 20px;
}

.page-about .index-list {
  list-style: none;
  margin: 0 0 32px;
  padding: 0;
  display: grid;
  gap: 4px;
}

.page-about .index-list a {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 8px 0;
  color: var(--color-text);
  text-decoration: none;
  font-weight: 500;
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition), color var(--transition);
}

.page-about .index-list a:hover {
  color: var(--color-primary);
  border-bottom-color: var(--color-border);
}

.page-about .index-num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-accent);
}

.page-about .index-coord {
  margin-top: 32px;
  padding: 16px;
  border: 1px dashed var(--color-border);
  display: grid;
  gap: 6px;
}

.page-about .coord-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  text-transform: uppercase;
  color: var(--color-text-secondary);
}

.page-about .coord-value {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--color-text);
  line-height: 1.6;
}

.page-about .coord-note {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

.page-about .about-section {
  position: relative;
  margin-bottom: 72px;
  scroll-margin-top: calc(var(--header-height) + 24px);
}

.page-about .about-section:last-child {
  margin-bottom: 0;
}

.page-about .about-section h2 {
  font-family: var(--font-headline);
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  font-weight: 400;
  line-height: 1.2;
  margin: 8px 0 16px;
}

.page-about .section-lead {
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 32px;
  max-width: 720px;
}

.page-about .about-section .section-index {
  margin-bottom: 4px;
}

.page-about .story-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
  align-items: start;
}

.page-about .story-copy p {
  line-height: 1.7;
  color: var(--color-text-secondary);
  margin-bottom: 16px;
}

.page-about .brand-badge {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-top: 28px;
  padding: 16px 20px;
  border: 1px solid var(--color-border);
  background: var(--color-panel);
  border-left: 3px solid var(--color-gold);
  max-width: 480px;
}

.page-about .badge-svg {
  width: 72px;
  height: 72px;
  flex-shrink: 0;
}

.page-about .badge-title {
  font-family: var(--font-headline);
  font-size: 1.05rem;
  letter-spacing: 0.08em;
  color: var(--color-text);
  margin: 0;
}

.page-about .badge-sub {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin: 4px 0 0;
}

.page-about .story-figure {
  position: relative;
  margin: 0;
}

.page-about .story-figure::before {
  content: "";
  position: absolute;
  inset: -12px 12px 12px -12px;
  background:
    linear-gradient(var(--color-border) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-border) 1px, transparent 1px);
  background-size: 24px 24px;
  opacity: 0.35;
  pointer-events: none;
  z-index: 0;
}

.page-about .story-img {
  position: relative;
  z-index: 1;
  width: 100%;
  height: auto;
  border: 1px dashed var(--color-border);
}

.page-about figcaption {
  margin-top: 8px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--color-text-secondary);
}

.page-about .timeline-wrap {
  margin-top: 32px;
}

.page-about .timeline-svg {
  width: 100%;
  height: auto;
  max-height: 160px;
  margin-bottom: 8px;
}

.page-about .timeline-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0;
}

.page-about .timeline-list details {
  border-bottom: 1px solid var(--color-border);
}

.page-about .timeline-list summary {
  display: grid;
  grid-template-columns: 56px 1fr 24px;
  align-items: center;
  gap: 12px;
  padding: 16px 8px;
  cursor: pointer;
  list-style: none;
  transition: background var(--transition);
}

.page-about .timeline-list summary::-webkit-details-marker {
  display: none;
}

.page-about .timeline-list summary:hover {
  background: rgba(0, 200, 83, 0.06);
}

.page-about .tl-year {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--color-accent);
}

.page-about .tl-title {
  font-weight: 600;
  color: var(--color-text);
}

.page-about .tl-chevron::before {
  content: "";
  display: block;
  width: 10px;
  height: 10px;
  border-right: 2px solid var(--color-text-secondary);
  border-bottom: 2px solid var(--color-text-secondary);
  transform: rotate(45deg);
  transition: transform var(--transition);
}

.page-about .timeline-list details[open] .tl-chevron::before {
  transform: rotate(-135deg);
}

.page-about .timeline-list details p {
  margin: 0;
  padding: 0 8px 16px 80px;
  color: var(--color-text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
}

.page-about .capability-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
  align-items: start;
}

.page-about .capability-figure {
  position: relative;
  margin: 0;
}

.page-about .capability-figure::before {
  content: "";
  position: absolute;
  inset: 12px -12px -12px 12px;
  background:
    linear-gradient(var(--color-border) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-border) 1px, transparent 1px);
  background-size: 28px 28px;
  opacity: 0.3;
  pointer-events: none;
  z-index: 0;
}

.page-about .capability-radar-img {
  position: relative;
  z-index: 1;
  width: 100%;
  height: auto;
  border: 1px solid var(--color-border);
}

.page-about .capability-stats {
  display: grid;
  gap: 10px;
}

.page-about .stat-card {
  display: grid;
  grid-template-columns: 40px 1fr;
  column-gap: 14px;
  padding: 14px 16px;
  background: var(--color-panel);
  border-left: 2px solid var(--color-primary);
}

.page-about .stat-glyph {
  grid-row: 1 / 3;
  width: 36px;
  height: 36px;
  align-self: center;
}

.page-about .stat-body {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  flex-wrap: wrap;
}

.page-about .stat-label {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-secondary);
}

.page-about .stat-value {
  font-family: var(--font-headline);
  font-size: 1.5rem;
  font-weight: 500;
  color: var(--color-text);
  line-height: 1;
}

.page-about .stat-unit {
  font-size: 1rem;
  color: var(--color-accent);
  margin-left: 2px;
}

.page-about .stat-note {
  grid-column: 2;
  font-size: 0.82rem;
  color: var(--color-text-secondary);
  margin: 2px 0 0;
}

.page-about .capability-footnote {
  margin-top: 28px;
  padding: 16px 20px;
  border: 1px dashed var(--color-border);
  color: var(--color-text-secondary);
  line-height: 1.6;
  font-size: 0.92rem;
}

.page-about .capability-footnote a {
  color: var(--color-primary);
  text-decoration: none;
}

.page-about .current-version {
  margin: 32px 0;
  padding: 28px;
  background: var(--color-panel);
  border: 1px solid var(--color-border);
  position: relative;
}

.page-about .current-version::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--color-primary);
}

.page-about .version-head {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.page-about .version-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  padding: 4px 10px;
  background: var(--color-primary-dark);
  color: var(--color-accent);
  border: 1px solid var(--color-border);
}

.page-about .current-version h3 {
  font-family: var(--font-headline);
  font-size: 1.6rem;
  font-weight: 400;
  margin: 0;
  color: var(--color-text);
}

.page-about .version-features {
  list-style: none;
  padding: 0;
  margin: 0 0 20px;
  display: grid;
  gap: 10px;
}

.page-about .version-features li {
  position: relative;
  padding-left: 24px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.page-about .version-features li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.55em;
  width: 12px;
  height: 2px;
  background: var(--color-accent);
}

.page-about .version-meta {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin: 0 0 20px;
}

.page-about .version-figure {
  position: relative;
  margin: 32px 0;
}

.page-about .version-img {
  width: 100%;
  height: auto;
  border: 1px dashed var(--color-border);
}

.page-about .version-list {
  margin-top: 32px;
}

.page-about .version-list h3 {
  font-family: var(--font-headline);
  font-size: 1.25rem;
  font-weight: 500;
  margin-bottom: 8px;
  color: var(--color-text);
}

.page-about .version-note {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  margin: 0 0 16px;
}

.page-about .version-item {
  background: var(--color-panel);
  margin-bottom: 8px;
  border: 1px solid var(--color-border);
  transition: border-color var(--transition);
}

.page-about .version-item[open] {
  border-color: var(--color-primary);
}

.page-about .version-item summary {
  display: grid;
  grid-template-columns: 40px 1fr 20px;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  cursor: pointer;
  list-style: none;
}

.page-about .version-item summary::-webkit-details-marker {
  display: none;
}

.page-about .version-item summary::after {
  content: "";
  width: 8px;
  height: 8px;
  border-right: 2px solid var(--color-text-secondary);
  border-bottom: 2px solid var(--color-text-secondary);
  transform: rotate(45deg);
  transition: transform var(--transition);
  justify-self: end;
}

.page-about .version-item[open] summary::after {
  transform: rotate(-135deg);
}

.page-about .ver-no {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--color-accent);
  border: 1px solid var(--color-border);
  padding: 2px 6px;
  text-align: center;
}

.page-about .ver-name {
  font-weight: 600;
  color: var(--color-text);
}

.page-about .ver-year {
  display: none;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
}

.page-about .version-item ul {
  margin: 0;
  padding: 0 16px 16px 68px;
  display: grid;
  gap: 6px;
}

.page-about .version-item li {
  color: var(--color-text-secondary);
  font-size: 0.92rem;
  line-height: 1.6;
}

.page-about .version-help {
  margin-top: 24px;
  color: var(--color-text-secondary);
}

.page-about .version-help a {
  color: var(--color-primary);
  text-decoration: none;
}

@media (max-width: 767px) {
  .page-about .hero-bg-line {
    display: none;
  }

  .page-about .hero-inner {
    padding-bottom: 8px;
  }

  .page-about .archive-index {
    display: none;
  }
}

@media (min-width: 768px) {
  .page-about .story-grid {
    grid-template-columns: 1fr 360px;
    gap: 48px;
  }
}

@media (min-width: 900px) {
  .page-about .capability-grid {
    grid-template-columns: minmax(0, 1fr) minmax(280px, 380px);
  }

  .page-about .version-item summary {
    grid-template-columns: 48px 1fr auto 20px;
  }

  .page-about .ver-year {
    display: inline-block;
  }
}

@media (min-width: 1024px) {
  .page-about .archive-layout {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: 64px;
    margin-top: 64px;
  }

  .page-about .archive-index {
    position: sticky;
    top: calc(var(--header-height) + 32px);
    align-self: start;
  }

  .page-about .hero-inner {
    padding: 24px 0 8px;
  }
}