.page-about {
  --about-rail-w: 288px;
  --about-chapter-gap: clamp(3rem, 7vw, 5.5rem);
  --about-rail-bg: linear-gradient(180deg, #E4EEF3 0%, #E2F0FA 100%);
  --about-ink: #17211E;
  --about-muted: #43534D;
  --about-line: #9EB7C4;
  background: #F5F2EC;
}

.page-about .about-layout {
  display: block;
  min-width: 0;
}

.page-about .about-rail {
  background: var(--about-rail-bg);
  border-bottom: 2px solid var(--about-ink);
  padding: 1rem 1.25rem 1.25rem;
  overflow: hidden;
}

.page-about .rail-stick {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.page-about .rail-eyebrow {
  margin: 0;
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: #0E5A8A;
}

.page-about .rail-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.5rem;
}

.page-about .rail-stat {
  background: rgba(255, 255, 255, 0.55);
  border: 1px solid var(--about-line);
  border-radius: 8px;
  padding: 0.625rem 0.5rem;
  text-align: center;
  min-width: 0;
}

.page-about .rail-stat-num {
  display: block;
  font-family: var(--font-display);
  font-size: clamp(1rem, 3.6vw, 1.375rem);
  font-weight: 900;
  line-height: 1.1;
  color: var(--about-ink);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.page-about .rail-stat-tag {
  display: block;
  font-size: 0.75rem;
  line-height: 1.4;
  color: var(--about-muted);
  margin-top: 0.125rem;
  white-space: nowrap;
}

.page-about .rail-link {
  display: inline-block;
  font-family: var(--font-display);
  font-size: 0.9375rem;
  font-weight: 700;
  color: #0E6B48;
  text-decoration: none;
  border-bottom: 2px solid #0E6B48;
  padding-bottom: 0.125rem;
  align-self: flex-start;
}

.page-about .rail-link:hover {
  color: #B45E1A;
  border-bottom-color: #B45E1A;
}

.page-about .rail-note {
  margin: 0;
  font-family: var(--font-body);
  font-size: 0.8125rem;
  line-height: 1.6;
  color: var(--about-muted);
}

.page-about .about-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
  min-width: 0;
}

.page-about .breadcrumb {
  margin-bottom: 1.5rem;
  font-family: var(--font-display);
  font-size: 0.875rem;
  color: var(--about-muted);
}

.page-about .breadcrumb a {
  color: #0E5A8A;
  text-decoration: none;
}

.page-about .breadcrumb a:hover {
  text-decoration: underline;
}

.page-about .crumb-sep {
  margin: 0 0.5rem;
  color: var(--about-line);
}

.page-about .about-hero {
  padding: 1.5rem 0 2.25rem;
  border-bottom: 2px solid var(--about-ink);
  margin-bottom: 3rem;
}

.page-about .hero-kicker {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #B45E1A;
}

.page-about .about-hero h1 {
  margin: 0 0 1rem;
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.4rem);
  font-weight: 900;
  line-height: 1.15;
  color: var(--about-ink);
}

.page-about .hero-intro {
  margin: 0;
  max-width: 680px;
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--about-muted);
}

.page-about .about-chapter {
  margin-bottom: var(--about-chapter-gap);
  padding-top: 2.5rem;
  border-top: 1px solid var(--about-line);
  min-width: 0;
}

.page-about .chapter-head {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.page-about .chapter-number {
  font-family: var(--font-display);
  font-size: clamp(2.75rem, 6vw, 4rem);
  font-weight: 900;
  line-height: 0.85;
  letter-spacing: -0.04em;
  color: rgba(23, 33, 30, 0.16);
  min-width: clamp(3.25rem, 6vw, 4.5rem);
  user-select: none;
}

.page-about #version .chapter-number,
.page-about #coverage .chapter-number,
.page-about #credentials .chapter-number,
.page-about #contact .chapter-number {
  color: rgba(23, 33, 30, 0.13);
}

.page-about .chapter-head h2 {
  margin: 0 0 0.25rem;
  font-family: var(--font-display);
  font-size: clamp(1.35rem, 2.6vw, 2rem);
  font-weight: 800;
  line-height: 1.2;
  color: var(--about-ink);
}

.page-about .chapter-subtitle {
  margin: 0;
  font-family: var(--font-display);
  font-size: 0.875rem;
  font-weight: 700;
  color: #B45E1A;
}

.page-about .chapter-intro {
  margin: 0 0 1.5rem;
  max-width: 640px;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.75;
  color: var(--about-muted);
}

.page-about .about-origin-grid {
  display: grid;
  gap: 1.5rem;
  align-items: start;
}

.page-about .about-origin-text p {
  margin: 0 0 1rem;
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.85;
  color: var(--about-ink);
}

.page-about .about-origin-text p:last-child {
  margin-bottom: 0;
}

.page-about .about-origin-text a {
  color: #0E5A8A;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .about-origin-text a:hover {
  color: #B45E1A;
}

.page-about .about-origin-image,
.page-about .about-network-image,
.page-about .about-version-image {
  margin: 0;
}

.page-about .about-origin-image img,
.page-about .about-network-image img,
.page-about .about-version-image img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 2px solid var(--about-ink);
  border-radius: var(--radius);
  box-shadow: 4px 4px 0 rgba(23, 33, 30, 0.32);
}

.page-about .about-origin-image figcaption,
.page-about .about-network-image figcaption,
.page-about .about-version-image figcaption {
  margin-top: 0.5rem;
  font-family: var(--font-body);
  font-size: 0.8125rem;
  line-height: 1.6;
  color: var(--about-muted);
}

.page-about .about-timeline {
  margin: 1.5rem 0 2rem;
  padding-left: 1.5rem;
  border-left: 3px solid var(--about-ink);
  display: grid;
  gap: 2rem;
}

.page-about .timeline-item {
  position: relative;
  min-width: 0;
}

.page-about .timeline-item::before {
  content: '';
  position: absolute;
  left: calc(-1.5rem - 6px);
  top: 0.625rem;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  border: 2px solid var(--about-ink);
  background: #E4EEF3;
}

.page-about .timeline-item[data-season="summer"]::before {
  background: #0E5A8A;
}

.page-about .timeline-item[data-season="autumn"]::before {
  background: #E8A33D;
}

.page-about .timeline-item[data-season="winter"]::before {
  background: #9EB7C4;
}

.page-about .timeline-marker {
  display: inline-block;
  margin-bottom: 0.5rem;
  padding: 0.25rem 0.75rem;
  font-family: var(--font-display);
  font-size: 0.875rem;
  font-weight: 900;
  line-height: 1.4;
  color: #0E5A8A;
  border: 2px solid #0E5A8A;
  border-radius: 999px;
}

.page-about .timeline-item[data-season="autumn"] .timeline-marker {
  color: #B45E1A;
  border-color: #B45E1A;
}

.page-about .timeline-item[data-season="winter"] .timeline-marker {
  color: #43534D;
  border-color: #9EB7C4;
}

.page-about .timeline-body {
  border-radius: var(--radius);
  padding: 0.75rem 0;
  transition: background 0.2s ease, box-shadow 0.2s ease, padding 0.2s ease;
}

.page-about .timeline-item:hover .timeline-body,
.page-about .timeline-item:focus-within .timeline-body {
  background: #F5F2EC;
  box-shadow: 3px 3px 0 rgba(158, 183, 196, 0.7);
  padding: 0.75rem 1rem;
}

.page-about .timeline-body h3 {
  margin: 0 0 0.375rem;
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 800;
  color: var(--about-ink);
}

.page-about .timeline-body p {
  margin: 0;
  font-family: var(--font-body);
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--about-muted);
}

.page-about .about-version-image {
  max-width: 420px;
}

.page-about .about-network-grid {
  display: grid;
  gap: 1.5rem;
  align-items: center;
}

.page-about .network-stats {
  display: grid;
  gap: 1rem;
}

.page-about .stat-card {
  padding: 1.25rem;
  background: #FFFFFF;
  border: 2px solid var(--about-ink);
  border-radius: var(--radius);
  box-shadow: 4px 4px 0 rgba(23, 33, 30, 0.32);
  border-top-width: 6px;
}

.page-about .stat-card[data-season="summer"] {
  border-top-color: #0E5A8A;
}

.page-about .stat-card[data-season="autumn"] {
  border-top-color: #E8A33D;
}

.page-about .stat-card[data-season="winter"] {
  border-top-color: #9EB7C4;
}

.page-about .stat-card-num {
  display: block;
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 2.75rem);
  font-weight: 900;
  line-height: 1.1;
  color: #B45E1A;
  font-variant-numeric: tabular-nums;
}

.page-about .stat-card-label {
  display: inline-block;
  margin-top: 0.25rem;
  font-family: var(--font-display);
  font-size: 0.875rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  color: var(--about-ink);
}

.page-about .stat-card-note {
  margin: 0.5rem 0 0;
  font-family: var(--font-body);
  font-size: 0.875rem;
  line-height: 1.65;
  color: var(--about-muted);
}

.page-about .about-credential-grid {
  display: grid;
  gap: 1rem;
}

.page-about .credential-card {
  background: #FFFFFF;
  border: 2px solid var(--about-ink);
  border-radius: var(--radius);
  box-shadow: 4px 4px 0 rgba(23, 33, 30, 0.32);
  overflow: hidden;
}

.page-about .credential-card summary {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.375rem;
  list-style: none;
  cursor: pointer;
  padding: 1.25rem;
  position: relative;
  padding-right: 3rem;
}

.page-about .credential-card summary::-webkit-details-marker {
  display: none;
}

.page-about .credential-card summary::after {
  content: '+';
  position: absolute;
  right: 1.25rem;
  top: 1.25rem;
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 900;
  line-height: 1;
  color: #0E5A8A;
}

.page-about .credential-card[open] summary::after {
  content: '−';
  color: #B45E1A;
}

.page-about .credential-name {
  font-family: var(--font-display);
  font-size: 0.9375rem;
  font-weight: 800;
  color: var(--about-ink);
  padding-right: 0.5rem;
}

.page-about .credential-scope {
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 700;
  color: #43534D;
}

.page-about .credential-detail {
  padding: 0 1.25rem 1.25rem;
  border-top: 1px solid #E4EEF3;
}

.page-about .credential-detail p {
  margin: 0.75rem 0 0;
  font-family: var(--font-body);
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--about-muted);
}

.page-about .about-honor {
  margin-top: 1.5rem;
  padding: 1rem 1.25rem;
  background: #E2F0FA;
  border-left: 4px solid #0E5A8A;
  border-radius: 0 8px 8px 0;
}

.page-about .honor-line {
  margin: 0;
  font-family: var(--font-body);
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--about-ink);
}

.page-about .about-contact-row {
  display: grid;
  gap: 1rem;
}

.page-about .contact-card {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  padding: 1.25rem;
  background: #FFFFFF;
  border: 2px solid var(--about-ink);
  border-radius: var(--radius);
  box-shadow: 4px 4px 0 rgba(23, 33, 30, 0.32);
}

.page-about .contact-title {
  margin: 0 0 0.375rem;
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  color: #0E6B48;
}

.page-about .contact-value {
  margin: 0 0 0.75rem;
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 700;
  color: var(--about-ink);
  word-break: break-all;
  font-variant-numeric: tabular-nums;
}

.page-about .contact-note {
  margin: 1.25rem 0 0;
  padding: 0.875rem 1rem;
  font-family: var(--font-body);
  font-size: 0.875rem;
  line-height: 1.7;
  color: var(--about-muted);
  background: #E3F2EB;
  border-radius: 8px;
}

.page-about .about-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 2px solid var(--about-ink);
}

.page-about .about-links a {
  padding: 0.375rem 1rem;
  font-family: var(--font-display);
  font-size: 0.875rem;
  font-weight: 700;
  color: #0E5A8A;
  text-decoration: none;
  border: 1px solid var(--about-line);
  border-radius: 999px;
}

.page-about .about-links a:hover {
  background: #E2F0FA;
  border-color: #0E5A8A;
}

@media (min-width: 1024px) {
  .page-about .about-layout {
    display: grid;
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 0;
    height: 100vh;
    padding: 2.25rem 1.5rem 2rem;
    border-right: 2px solid var(--about-ink);
    border-bottom: 0;
    box-sizing: border-box;
  }

  .page-about .rail-stick {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
  }

  .page-about .rail-stats {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .page-about .rail-stat {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: 0.75rem;
    text-align: left;
    background: transparent;
    border: 0;
    border-bottom: 1px solid #9EB7C4;
    border-radius: 0;
    padding: 0.875rem 0;
  }

  .page-about .rail-stat-num {
    font-size: 1.5rem;
    white-space: normal;
  }

  .page-about .rail-stat-tag {
    margin: 0;
    font-size: 0.8125rem;
    white-space: normal;
  }

  .page-about .about-content {
    padding: 2.75rem 3rem 4rem;
    max-width: 100%;
  }

  .page-about .about-origin-grid {
    grid-template-columns: minmax(0, 1.2fr) minmax(280px, 0.8fr);
    gap: 2.5rem;
  }

  .page-about .about-origin-image {
    margin-top: 0.5rem;
  }

  .page-about .about-network-grid {
    grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.1fr);
    gap: 2.5rem;
  }

  .page-about .about-version-image {
    max-width: 400px;
    margin-left: auto;
    margin-right: 0;
  }

  .page-about .about-credential-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 1.25rem;
  }

  .page-about .credential-card summary {
    flex-direction: column;
    padding-right: 1.25rem;
  }

  .page-about .contact-card:nth-child(2) {
    transform: translateY(0.75rem);
  }

  .page-about .contact-card:nth-child(4) {
    transform: translateY(0.75rem);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .timeline-body {
    transition: none;
  }
}