.page-about {
  --about-rail: clamp(220px, 23vw, 272px);
  --about-accent-bg: rgba(0, 212, 255, 0.07);
  --about-warm-bg: rgba(255, 106, 0, 0.08);
  --about-grid-bg:
    linear-gradient(rgba(0, 212, 255, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 212, 255, 0.045) 1px, transparent 1px);
  --about-grid-size: 46px 46px;
}

.page-about__hero {
  position: relative;
  overflow: hidden;
  padding: 36px 0 56px;
  background-color: var(--c-bg-deep);
}

.page-about__hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: var(--about-grid-bg);
  background-size: var(--about-grid-size);
}

.page-about__hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: var(--line-grad);
}

.page-about__hero .container {
  position: relative;
  z-index: 1;
}

.page-about__title {
  max-width: 860px;
  margin: 14px 0 0;
  font-size: clamp(30px, 5.6vw, 54px);
  line-height: 1.12;
  letter-spacing: 0.01em;
}

.page-about__title-sep {
  margin: 0 8px;
  color: var(--c-accent-warm);
  font-weight: 400;
}

.page-about__title-accent {
  color: var(--c-accent);
}

.page-about__lead {
  max-width: 680px;
  margin: 18px 0 28px;
  font-family: var(--font-serif);
  font-size: 16px;
  line-height: 1.9;
  color: var(--c-mist);
}

.page-about__facts {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  max-width: 760px;
  overflow: hidden;
  background: var(--c-line);
  border: 1px solid var(--c-line);
  border-radius: var(--radius-md);
}

.page-about__fact {
  min-height: 92px;
  padding: 16px 18px;
  background: var(--c-bg-card);
}

.page-about__fact-num {
  display: block;
  font-size: 30px;
  font-weight: 900;
  letter-spacing: -0.03em;
  color: var(--c-accent);
}

.page-about__fact-label {
  display: block;
  margin-top: 5px;
  font-size: 13px;
  color: var(--c-mist);
}

.page-about__layout {
  display: block;
  padding: 40px 0 72px;
}

.page-about__toc {
  position: relative;
  margin: 0 0 28px;
  padding: 20px 16px 16px;
  background:
    linear-gradient(180deg, rgba(255, 106, 0, 0.05), transparent 40%),
    var(--c-bg-card);
  border: 1px solid var(--c-line);
  border-left: 3px solid var(--c-accent-warm);
  border-radius: var(--radius-md);
}

.page-about__toc::before {
  content: "目录";
  position: absolute;
  top: -11px;
  left: 14px;
  padding: 5px 12px;
  background: var(--c-accent-warm);
  color: #ffffff;
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.1em;
  border-radius: var(--radius-sm) var(--radius-sm) 0 0;
}

.page-about__toc-title {
  margin: 8px 0 10px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--c-mist);
}

.page-about__toc-list {
  display: flex;
  gap: 4px;
  overflow-x: auto;
  list-style: none;
  margin: 0;
  padding: 2px 2px 6px;
  scrollbar-width: thin;
}

.page-about__toc-list li {
  flex-shrink: 0;
}

.page-about__toc-link {
  display: block;
  padding: 9px 12px;
  border-radius: var(--radius-sm);
  color: var(--c-mist);
  font-size: 14px;
  font-weight: 600;
  white-space: nowrap;
  text-decoration: none;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.page-about__toc-link:hover,
.page-about__toc-link:focus-visible {
  color: var(--c-accent);
  background: var(--about-accent-bg);
}

.page-about__toc-note {
  margin: 4px 2px 0;
  font-size: 12px;
  color: var(--c-mist);
  opacity: 0.8;
}

.page-about__content {
  min-width: 0;
}

.page-about__section {
  position: relative;
  scroll-margin-top: calc(var(--header-h) + 24px);
  padding-bottom: 48px;
  border-top: 1px solid var(--c-line);
}

.page-about__section:target {
  border-top-color: var(--c-accent);
}

.page-about__section:target .page-about__section-hd h2 {
  color: var(--c-accent);
}

.page-about__section-hd {
  margin-bottom: 20px;
}

.page-about__section-hd .section-label {
  margin-bottom: 8px;
}

.page-about__section-hd h2 {
  margin: 0;
  font-size: clamp(24px, 3.6vw, 34px);
  letter-spacing: 0.02em;
  transition: color 0.2s ease;
}

.page-about__section-text {
  max-width: 720px;
  margin: 0 0 18px;
  color: var(--c-mist);
  line-height: 1.8;
}

.page-about__history-img {
  margin: 6px 0 24px;
  overflow: hidden;
  border-radius: var(--radius-lg);
}

.page-about__timeline {
  position: relative;
  list-style: none;
  margin: 8px 0 0;
  padding: 8px 0 4px;
}

.page-about__timeline::before {
  content: "";
  position: absolute;
  top: 12px;
  bottom: 12px;
  left: 8px;
  width: 2px;
  border-radius: 999px;
  background: linear-gradient(180deg, var(--c-accent), var(--c-accent-warm));
}

.page-about__timeline-item {
  position: relative;
  padding: 0 0 32px 36px;
}

.page-about__timeline-item:last-child {
  padding-bottom: 0;
}

.page-about__timeline-node {
  position: absolute;
  top: 6px;
  left: -1px;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border: 2px solid var(--c-accent);
  border-radius: 50%;
  background: var(--c-bg-deep);
  box-shadow: 0 0 12px rgba(0, 212, 255, 0.22);
}

.page-about__timeline-node::after {
  content: "";
  display: block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--c-accent);
}

.page-about__timeline-card {
  padding: 18px 20px;
  background: var(--c-bg-card);
  border: 1px solid var(--c-line);
  border-radius: var(--radius-md);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.page-about__timeline-card:hover {
  border-color: rgba(0, 212, 255, 0.35);
  box-shadow: var(--shadow-glow);
}

.page-about__timeline-year {
  display: inline-block;
  margin-bottom: 8px;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.08em;
  color: var(--c-accent-warm);
}

.page-about__timeline-card h3 {
  margin: 0 0 8px;
  font-size: 17px;
  font-weight: 700;
}

.page-about__timeline-card p {
  margin: 0;
  color: var(--c-mist);
  font-size: 14px;
  line-height: 1.7;
}

.page-about__cap-grid {
  display: grid;
  gap: 16px;
  margin-top: 24px;
}

.page-about__cap-card {
  padding: clamp(20px, 3vw, 28px);
}

.page-about__cap-card h3 {
  margin: 0 0 10px;
  font-size: 18px;
}

.page-about__cap-card p {
  margin: 0;
  color: var(--c-mist);
  font-size: 14px;
  line-height: 1.7;
}

.page-about__cap-index {
  margin: 0 0 18px;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0.08em;
  color: var(--c-accent-warm);
}

.page-about__cap-note {
  margin-top: 24px;
  padding: 18px 20px;
  background: var(--about-accent-bg);
  border-left: 3px solid var(--c-accent);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.page-about__cap-note p {
  margin: 0;
  color: var(--c-white);
  font-size: 15px;
  line-height: 1.8;
}

.page-about__cert-grid {
  display: grid;
  gap: 24px;
  margin-top: 24px;
}

.page-about__cert-img {
  overflow: hidden;
  border-radius: var(--radius-lg);
}

.page-about__cert-list {
  display: grid;
  gap: 14px;
}

.page-about__cert-item {
  padding: 18px 20px;
  background: var(--c-bg-card);
  border: 1px solid var(--c-line);
  border-radius: var(--radius-md);
}

.page-about__cert-item p {
  margin: 12px 0 0;
  color: var(--c-mist);
  font-size: 14px;
  line-height: 1.7;
}

.page-about__team-grid {
  display: grid;
  gap: 24px;
  margin-top: 24px;
}

.page-about__team-stat {
  margin: 0 0 12px;
  color: var(--c-white);
  font-size: 16px;
}

.page-about__team-stat strong {
  margin-right: 6px;
  font-size: 30px;
  font-weight: 900;
  color: var(--c-accent);
}

.page-about__team-text {
  margin: 16px 0 0;
  color: var(--c-mist);
  font-size: 14px;
  line-height: 1.8;
}

.page-about__team-img {
  overflow: hidden;
  border-radius: var(--radius-lg);
}

.page-about__team-foot {
  margin-top: 22px;
  padding: 16px 18px;
  background: var(--about-warm-bg);
  border: 1px solid rgba(255, 106, 0, 0.25);
  border-radius: var(--radius-md);
}

.page-about__team-foot p {
  margin: 0;
  color: var(--c-mist);
  font-size: 14px;
  line-height: 1.7;
}

.page-about__explore-grid {
  display: grid;
  gap: 14px;
  margin-top: 24px;
}

.page-about__explore-card {
  display: block;
  padding: 20px;
  color: inherit;
  text-decoration: none;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.page-about__explore-card h3 {
  margin: 0 0 8px;
  font-size: 18px;
}

.page-about__explore-card p {
  margin: 0;
  color: var(--c-mist);
  font-size: 14px;
  line-height: 1.7;
}

.page-about__explore-card:hover,
.page-about__explore-card:focus-visible {
  transform: translateY(-2px);
  border-color: rgba(0, 212, 255, 0.4);
  box-shadow: var(--shadow-glow);
}

.page-about__explore-arrow {
  display: inline-block;
  margin-bottom: 12px;
  color: var(--c-accent);
  font-size: 20px;
  transition: transform 0.2s ease, color 0.2s ease;
}

.page-about__explore-card:hover .page-about__explore-arrow,
.page-about__explore-card:focus-visible .page-about__explore-arrow {
  transform: translateX(4px);
  color: var(--c-accent-warm);
}

@media (min-width: 720px) {
  .page-about__facts {
    grid-template-columns: repeat(4, 1fr);
  }

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

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

@media (min-width: 860px) {
  .page-about__cert-grid {
    grid-template-columns: minmax(220px, 0.8fr) minmax(0, 1.2fr);
    gap: 32px;
    align-items: center;
  }

  .page-about__team-grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 32px;
    align-items: center;
  }
}

@media (min-width: 980px) {
  .page-about__hero {
    padding: 48px 0 72px;
  }

  .page-about__layout {
    display: grid;
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(40px, 6vw, 80px);
    align-items: start;
    padding-top: 60px;
    padding-bottom: 96px;
  }

  .page-about__toc {
    position: sticky;
    top: calc(var(--header-h) + 28px);
    margin-top: 0;
  }

  .page-about__toc-list {
    display: block;
    overflow: visible;
    padding: 0;
  }

  .page-about__toc-list li {
    flex-shrink: 1;
  }

  .page-about__toc-link {
    margin-bottom: 4px;
    border-left: 2px solid var(--c-line);
    border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  }

  .page-about__toc-link:hover,
  .page-about__toc-link:focus-visible {
    border-left-color: var(--c-accent);
  }

  .page-about__timeline {
    padding-top: 8px;
  }

  .page-about__timeline::before {
    left: 50%;
    transform: translateX(-1px);
  }

  .page-about__timeline-item {
    width: 50%;
    padding: 0 34px 36px 0;
    text-align: right;
  }

  .page-about__timeline-item:nth-child(even) {
    margin-left: 50%;
    padding: 0 0 36px 34px;
    text-align: left;
  }

  .page-about__timeline-node {
    top: 6px;
    right: -10px;
    left: auto;
  }

  .page-about__timeline-item:nth-child(even) .page-about__timeline-node {
    right: auto;
    left: -10px;
  }
}