.page-about {
  --about-cyan: var(--cyan);
  --about-violet: var(--violet);
  --about-orange: var(--orange);
  --about-gap: 28px;
}

.page-about .about-hero {
  padding: 48px 0 32px;
}

.page-about .about-hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr);
  gap: 40px;
  align-items: start;
}

.page-about .about-hero-main h1 {
  font-size: clamp(28px, 4vw, 44px);
  line-height: 1.2;
  margin: 12px 0 18px;
}

.page-about .about-hero-side {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
}

.page-about .hero-version-key {
  font-size: 12px;
  color: var(--muted);
  letter-spacing: 0.08em;
  margin: 0 0 6px;
}

.page-about .hero-version-val {
  font-size: 40px;
  font-weight: 700;
  color: var(--cyan);
  margin: 0 0 6px;
  line-height: 1;
}

.page-about .hero-version-note {
  font-size: 13px;
  color: var(--muted);
  margin: 0 0 18px;
}

.page-about .hero-meta {
  margin: 0;
  display: grid;
  gap: 10px;
}

.page-about .hero-meta-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  border-top: 1px solid var(--line);
  padding-top: 10px;
  font-size: 14px;
}

.page-about .hero-meta-row dt {
  color: var(--muted);
}

.page-about .hero-meta-row dd {
  margin: 0;
  text-align: right;
  color: var(--text);
}

.page-about .about-shell {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 48px;
  padding: 24px 0 64px;
}

.page-about .about-rail {
  position: sticky;
  top: calc(var(--header-h) + 24px);
  align-self: start;
}

.page-about .rail-title {
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--muted);
  margin: 0 0 12px;
}

.page-about .rail-track {
  display: grid;
  gap: 4px;
}

.page-about .rail-btn {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
  border-left: 2px solid transparent;
}

.page-about .rail-btn:hover {
  color: var(--text);
  background: var(--layer);
}

.page-about .rail-btn.is-current {
  color: var(--text);
  border-left-color: var(--cyan);
  background: var(--layer);
}

.page-about .rail-num {
  font-size: 12px;
  color: var(--dim);
}

.page-about .about-stream {
  display: grid;
  gap: 72px;
  min-width: 0;
}

.page-about .about-section {
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.page-about .about-section.is-offset {
  padding-left: 32px;
  border-left: 1px solid var(--line);
}

.page-about .about-section.is-narrow {
  max-width: 900px;
}

.page-about .about-prose p {
  margin: 0 0 14px;
  line-height: 1.75;
  color: var(--text);
}

.page-about .about-note {
  margin-top: 18px;
  padding: 14px 16px;
  background: var(--layer);
  border-left: 3px solid var(--cyan);
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--muted);
}

.page-about .about-note a {
  color: var(--cyan);
}

.page-about .use-list {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 16px;
}

.page-about .use-item {
  display: grid;
  grid-template-columns: 180px minmax(0, 1fr);
  gap: 20px;
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

.page-about .use-key {
  font-size: 13px;
  color: var(--cyan);
  letter-spacing: 0.04em;
}

.page-about .use-text h3 {
  margin: 0 0 6px;
  font-size: 17px;
}

.page-about .use-text p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
}

.page-about .version-track {
  list-style: none;
  margin: 28px 0 0;
  padding: 0 0 0 24px;
  border-left: 2px solid var(--line);
  display: grid;
  gap: 28px;
}

.page-about .version-node {
  position: relative;
}

.page-about .version-dot {
  position: absolute;
  left: -31px;
  top: 6px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--cyan);
  box-shadow: 0 0 0 4px var(--bg);
}

.page-about .version-node--violet .version-dot {
  background: var(--violet);
}

.page-about .version-node--orange .version-dot {
  background: var(--orange);
}

.page-about .version-tag {
  font-size: 12px;
  color: var(--muted);
  margin: 0 0 4px;
  letter-spacing: 0.06em;
}

.page-about .version-name {
  margin: 0 0 6px;
  font-size: 18px;
}

.page-about .version-body p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
}

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

.page-about .about-frame {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--panel);
}

.page-about .about-frame img {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .about-frame--wide {
  aspect-ratio: 16 / 9;
}

.page-about .about-frame--wide img {
  height: 100%;
  object-fit: cover;
}

.page-about .figure-cap {
  margin-top: 10px;
  font-size: 13px;
  color: var(--muted);
}

.page-about .flow-track {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
}

.page-about .flow-step {
  position: relative;
  padding: 20px 18px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.page-about .flow-num {
  display: block;
  font-size: 26px;
  font-weight: 700;
  color: var(--cyan);
  margin-bottom: 10px;
}

.page-about .flow-step h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.page-about .flow-step p {
  margin: 0;
  font-size: 13px;
  color: var(--muted);
  line-height: 1.7;
}

.page-about .team-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr);
  gap: 32px;
  margin-top: 28px;
  align-items: start;
}

.page-about .team-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.page-about .team-card {
  padding: 20px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.page-about .team-card:hover,
.page-about .team-card:focus-visible {
  border-color: var(--violet);
  transform: translateY(-2px);
}

.page-about .team-card-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 10px;
}

.page-about .team-name {
  margin: 0;
  font-size: 17px;
}

.page-about .team-count {
  font-size: 13px;
  color: var(--violet);
}

.page-about .team-summary {
  margin: 0 0 10px;
  font-size: 14px;
  line-height: 1.7;
  color: var(--text);
}

.page-about .team-detail {
  margin: 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  transition: max-height 0.3s ease, opacity 0.3s ease;
}

.page-about .team-card:hover .team-detail,
.page-about .team-card:focus-visible .team-detail {
  max-height: 240px;
  opacity: 1;
}

.page-about .team-figure {
  margin: 0;
}

.page-about .spec-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
  margin-top: 28px;
}

.page-about .spec-card {
  padding: 22px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  border-top: 3px solid var(--cyan);
}

.page-about .spec-card--violet {
  border-top-color: var(--violet);
}

.page-about .spec-card--orange {
  border-top-color: var(--orange);
}

.page-about .spec-key {
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin: 0 0 8px;
}

.page-about .spec-card h3 {
  margin: 0 0 12px;
  font-size: 17px;
}

.page-about .spec-card .marker-list {
  margin: 0;
  padding-left: 18px;
  font-size: 13px;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .cover-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
  margin: 28px 0;
}

.page-about .cover-cell {
  padding: 24px 20px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  border-left: 3px solid var(--cyan);
}

.page-about .cover-cell--violet {
  border-left-color: var(--violet);
}

.page-about .cover-cell--orange {
  border-left-color: var(--orange);
}

.page-about .cover-num {
  font-size: 44px;
  font-weight: 700;
  line-height: 1;
  margin: 0 0 8px;
  color: var(--text);
}

.page-about .cover-unit {
  font-size: 18px;
  margin-left: 4px;
  color: var(--muted);
}

.page-about .cover-label {
  margin: 0 0 8px;
  font-size: 14px;
  color: var(--text);
}

.page-about .cover-desc {
  margin: 0;
  font-size: 13px;
  color: var(--muted);
  line-height: 1.7;
}

.page-about .about-meta {
  margin-top: 20px;
  max-width: 560px;
}

@media (max-width: 960px) {
  .page-about .about-hero-grid,
  .page-about .about-shell,
  .page-about .team-layout {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .about-rail {
    position: static;
  }

  .page-about .rail-track {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
  }

  .page-about .flow-track,
  .page-about .spec-grid,
  .page-about .cover-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 640px) {
  .page-about .use-item {
    grid-template-columns: minmax(0, 1fr);
    gap: 8px;
  }

  .page-about .flow-track,
  .page-about .spec-grid,
  .page-about .cover-grid,
  .page-about .team-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .page-about .about-section.is-offset {
    padding-left: 16px;
  }
}