.page-about {
  --about-grid-line: rgba(44, 62, 80, 0.07);
  --about-grid-light: rgba(255, 255, 255, 0.04);
  --about-panel-shadow: 4px 4px 0 rgba(189, 195, 199, 0.45);
  background: var(--bg-wall);
  color: var(--text-dark);
  overflow-x: hidden;
}
.page-about__breadcrumb {
  padding-top: 14px;
  font-size: 13px;
}
.page-about__breadcrumb ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: 0;
  padding: 0;
}
.page-about__breadcrumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--accent-teal);
  font-family: var(--font-mono);
}
.page-about__breadcrumb a {
  color: var(--text-dark);
  text-decoration-line: underline;
  text-decoration-color: var(--accent-orange);
  text-underline-offset: 3px;
}
.page-about__hero {
  background:
    linear-gradient(var(--about-grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--about-grid-line) 1px, transparent 1px),
    var(--bg-card);
  background-size: 24px 24px;
  border-bottom: 3px solid var(--accent-orange);
}
.page-about__hero-inner {
  padding: 32px 0;
}
.page-about__hero-copy {
  max-width: 620px;
}
.page-about__hero-kicker {
  display: inline-block;
  background: var(--bg-main);
  color: var(--white);
  padding: 4px 10px;
  font-size: 12px;
  letter-spacing: 0.12em;
  margin: 0 0 12px;
}
.page-about__hero h1 {
  font-size: 28px;
  line-height: 1.2;
  margin: 0 0 10px;
  font-weight: 700;
  font-family: var(--font-sans);
}
.page-about__hero-desc {
  font-size: 15px;
  line-height: 1.75;
  margin: 0;
}
.page-about__fact-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  margin: 24px 0 0;
}
.page-about__fact-card {
  background: var(--bg-main);
  color: var(--white);
  border-top: 4px solid var(--accent-orange);
  padding: 14px 12px;
  margin: 0;
  position: relative;
}
.page-about__fact-card:nth-child(2) { border-top-color: var(--accent-teal); }
.page-about__fact-card:nth-child(3) { border-top-color: var(--status-blue); }
.page-about__fact-card:nth-child(4) { border-top-color: var(--tag-purple); }
.page-about__fact-card:nth-child(5) { border-top-color: var(--status-red); }
.page-about__fact-card:nth-child(6) { border-top-color: var(--tag-yellow); }
.page-about__fact-idx {
  position: absolute;
  top: 8px;
  right: 10px;
  font-size: 11px;
  color: rgba(255, 255, 255, 0.45);
}
.page-about__fact-card dt {
  font-size: 11px;
  letter-spacing: 0.14em;
  color: rgba(255, 255, 255, 0.6);
  margin: 0 0 4px;
}
.page-about__fact-num {
  font-size: 24px;
  font-weight: 700;
  line-height: 1.1;
  margin: 0;
  color: var(--white);
}
.page-about__fact-label {
  font-size: 12px;
  color: rgba(255, 255, 255, 0.8);
  margin: 4px 0 0;
}
.page-about__quicknav-bar {
  background: var(--bg-main);
  border-bottom: 2px solid var(--accent-orange);
}
.page-about__quick-nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  padding: 10px 0;
  gap: 0;
}
.page-about__quick-nav a {
  color: var(--white);
  text-decoration: none;
  font-size: 13px;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.2s, border-color 0.2s;
}
.page-about__quick-nav a:hover {
  color: var(--accent-orange);
  border-bottom-color: var(--accent-orange);
}
.page-about__quick-nav a + a {
  margin-left: 12px;
}
.page-about__quick-nav a + a::before {
  content: "/";
  margin-right: 12px;
  color: rgba(255, 255, 255, 0.4);
}
.page-about__section-index {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--accent-teal);
  margin: 0 0 4px;
  border-bottom: 2px solid var(--accent-orange);
  display: inline-block;
  padding-bottom: 2px;
}
.page-about__section-index--light {
  color: var(--accent-teal);
  background: rgba(255, 255, 255, 0.08);
  border-bottom-color: var(--accent-orange);
  padding: 2px 8px;
}
.page-about .section-head h2 {
  font-size: 26px;
  margin: 0 0 8px;
  line-height: 1.2;
  font-weight: 700;
}
.page-about .section-head {
  margin-bottom: 20px;
}
.page-about__scope {
  background: var(--bg-wall);
}
.page-about__scope-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
  padding-top: 12px;
}
.page-about__scope-copy p {
  font-size: 14px;
  line-height: 1.75;
  margin: 0 0 16px;
}
.page-about__scope-list {
  list-style: none;
  margin: 0 0 24px;
  padding: 0;
}
.page-about__scope-list li {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  padding: 11px 0;
  border-bottom: 1px solid var(--border-light);
  font-size: 14px;
  line-height: 1.5;
}
.page-about__scope-list .badge {
  flex: 0 0 auto;
}
.page-about__scope-num {
  font-weight: 700;
  color: var(--accent-orange);
}
.page-about__scope-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.page-about__scope-figure {
  position: relative;
  margin: 0;
  padding: 12px 12px 0 0;
}
.page-about__scope-figure::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 42px;
  width: 78%;
  height: 82%;
  border: 3px solid var(--accent-orange);
  z-index: 0;
  pointer-events: none;
}
.page-about__scope-figure img {
  position: relative;
  z-index: 1;
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  box-shadow: 4px 4px 0 var(--border-light);
}
.page-about__scope-figure figcaption {
  position: relative;
  z-index: 1;
  margin-top: 10px;
  font-size: 12px;
  color: var(--text-dark);
  text-align: right;
}
.page-about__taxonomy {
  background: var(--bg-main);
  color: var(--white);
  position: relative;
  overflow: hidden;
}
.page-about__taxonomy::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--about-grid-light) 1px, transparent 1px),
    linear-gradient(90deg, var(--about-grid-light) 1px, transparent 1px);
  background-size: 32px 32px;
  pointer-events: none;
}
.page-about__taxonomy .section-head {
  position: relative;
  z-index: 1;
}
.page-about__taxonomy .section-head h2 {
  color: var(--white);
}
.page-about__light-desc {
  color: rgba(245, 245, 220, 0.85);
  max-width: 640px;
  font-size: 14px;
  line-height: 1.7;
  margin: 0;
}
.page-about__taxonomy-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
  position: relative;
  z-index: 1;
}
.page-about__tree {
  display: grid;
  grid-template-columns: 1fr;
  gap: 12px;
}
.page-about__branch {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  box-shadow: 2px 2px 0 rgba(0, 0, 0, 0.18);
}
.page-about__branch-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 9px 12px;
  border-left: 6px solid var(--accent-orange);
  background: var(--bg-card);
}
.page-about__branch-head--teal { border-left-color: var(--accent-teal); }
.page-about__branch-head--purple { border-left-color: var(--tag-purple); }
.page-about__branch-head--blue { border-left-color: var(--status-blue); }
.page-about__branch-head--yellow { border-left-color: var(--tag-yellow); }
.page-about__branch-head--red { border-left-color: var(--status-red); }
.page-about__branch-head--green { border-left-color: var(--status-green); }
.page-about__branch-name {
  font-weight: 700;
  font-size: 15px;
  color: var(--text-dark);
}
.page-about__branch-count {
  background: var(--bg-main);
  color: var(--white);
  font-size: 12px;
  padding: 2px 8px;
}
.page-about__branch-list {
  list-style: none;
  margin: 0;
  padding: 10px 12px 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.page-about__branch-list li {
  font-size: 13px;
  border: 1px solid var(--border-light);
  background: var(--white);
  padding: 2px 10px;
  color: var(--text-dark);
  line-height: 1.6;
}
.page-about__taxonomy-figure {
  margin: 0;
}
.page-about__taxonomy-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  box-shadow: 6px 6px 0 rgba(0, 0, 0, 0.28);
}
.page-about__taxonomy-figcap {
  margin-top: 10px;
  font-size: 12px;
  color: rgba(255, 255, 255, 0.72);
  text-align: right;
}
.page-about__tags {
  background: var(--bg-card);
}
.page-about__tags-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
  padding-top: 12px;
}
.page-about__tags-copy p {
  font-size: 14px;
  line-height: 1.75;
  margin: 0 0 18px;
}
.page-about__tag-legend {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.page-about__tag-legend li {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 13px;
  color: var(--text-dark);
}
.page-about__tag-panel {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  padding: 20px;
  box-shadow: var(--about-panel-shadow);
}
.page-about__tag-panel-title {
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--accent-orange);
  margin: 0 0 14px;
}
.page-about__tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}
.page-about__timeline {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about__timeline-item {
  position: relative;
  padding: 0 0 24px 18px;
  border-left: 2px solid var(--border-light);
  margin-left: 4px;
}
.page-about__timeline-item:last-child {
  padding-bottom: 0;
  border-left-color: transparent;
}
.page-about__timeline-item::before {
  content: "";
  position: absolute;
  left: -7px;
  top: 6px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--accent-teal);
  border: 2px solid var(--bg-wall);
}
.page-about__timeline-item--current::before {
  background: var(--status-red);
  box-shadow: 0 0 0 4px rgba(231, 76, 60, 0.22);
}
.page-about__timeline-stamp {
  font-size: 13px;
  font-weight: 700;
  color: var(--accent-orange);
  margin-bottom: 6px;
  font-family: var(--font-mono);
}
.page-about__timeline-body {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  padding: 14px 16px;
  box-shadow: 2px 2px 0 var(--border-light);
}
.page-about__timeline-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}
.page-about__timeline-head .mono {
  font-size: 13px;
  color: var(--accent-orange);
  font-weight: 700;
}
.page-about__timeline-list {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about__timeline-list li {
  font-size: 14px;
  line-height: 1.6;
  padding: 5px 0;
  border-bottom: 1px dashed var(--border-light);
}
.page-about__timeline-list li:last-child {
  border-bottom: none;
}
.page-about__timeline-list li::before {
  content: "▸ ";
  color: var(--accent-teal);
}
.page-about__timeline-note {
  margin: 18px 0 0;
  font-size: 12px;
  color: var(--text-dark);
  letter-spacing: 0.06em;
}
.page-about__mobile {
  background: var(--bg-card);
}
.page-about__mobile-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
  align-items: center;
  padding-top: 12px;
}
.page-about__mobile-figure {
  margin: 0;
  text-align: center;
}
.page-about__mobile-figure img {
  display: inline-block;
  width: 100%;
  max-width: 220px;
  height: auto;
  border: 8px solid var(--bg-main);
  box-shadow: 0 10px 30px rgba(44, 62, 80, 0.3);
}
.page-about__mobile-figure figcaption {
  margin-top: 10px;
  font-size: 12px;
  color: var(--text-dark);
}
.page-about__mobile-desc {
  font-size: 14px;
  line-height: 1.75;
  margin: 0 0 16px;
}
.page-about__version-list {
  list-style: none;
  margin: 16px 0 24px;
  padding: 0;
}
.page-about__version-item {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 12px 0;
  border-top: 1px solid var(--border-light);
}
.page-about__version-item:last-child {
  border-bottom: 1px solid var(--border-light);
}
.page-about__version-copy {
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.page-about__version-copy strong {
  font-size: 15px;
  font-weight: 700;
}
.page-about__version-copy span {
  font-size: 13px;
  color: var(--text-dark);
  opacity: 0.72;
}
.page-about__guide {
  background: var(--bg-wall);
}
.page-about__guide-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}
.page-about__guide-card {
  display: flex;
  flex-direction: column;
  padding: 18px;
  background: var(--white);
  border: 1px solid var(--border-light);
  border-top: 4px solid var(--accent-teal);
  text-decoration: none;
  color: var(--text-dark);
  transition: transform 0.2s, box-shadow 0.2s;
}
.page-about__guide-card:hover {
  transform: translateY(-2px);
  box-shadow: 4px 4px 0 var(--border-light);
}
.page-about__guide-card:nth-child(2) { border-top-color: var(--accent-orange); }
.page-about__guide-card:nth-child(3) { border-top-color: var(--tag-purple); }
.page-about__guide-card:nth-child(4) { border-top-color: var(--status-blue); }
.page-about__guide-num {
  font-size: 12px;
  color: var(--accent-orange);
}
.page-about__guide-card h3 {
  margin: 8px 0 6px;
  font-size: 17px;
  font-weight: 700;
  color: var(--text-dark);
}
.page-about__guide-card p {
  margin: 0 0 12px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text-dark);
}
.page-about__guide-link {
  margin-top: auto;
  font-size: 12px;
  color: var(--status-blue);
}
@media (min-width: 640px) {
  .page-about__fact-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  .page-about__guide-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (min-width: 760px) {
  .page-about__tree {
    grid-template-columns: repeat(2, 1fr);
  }
  .page-about__mobile-figure img {
    max-width: 260px;
  }
}
@media (min-width: 900px) {
  .page-about__hero-inner {
    display: grid;
    grid-template-columns: 5fr 7fr;
    gap: 40px;
    align-items: center;
    padding: 48px 0;
  }
  .page-about__fact-grid {
    grid-template-columns: repeat(2, 1fr);
    margin: 0;
  }
  .page-about__scope-grid {
    grid-template-columns: 1.1fr 0.9fr;
    gap: 40px;
    align-items: center;
  }
  .page-about__taxonomy-grid {
    grid-template-columns: 1.15fr 0.85fr;
    gap: 40px;
    align-items: start;
  }
  .page-about__tags-grid {
    grid-template-columns: 0.85fr 1.15fr;
    gap: 40px;
    align-items: center;
  }
  .page-about__mobile-grid {
    grid-template-columns: 300px 1fr;
    gap: 40px;
  }
  .page-about__mobile-figure img {
    max-width: 300px;
  }
  .page-about__guide-grid {
    grid-template-columns: repeat(4, 1fr);
  }
  .page-about__hero h1 {
    font-size: 38px;
  }
  .page-about__hero-desc {
    font-size: 16px;
  }
}
@media (min-width: 1100px) {
  .page-about__tree {
    grid-template-columns: repeat(2, 1fr);
  }
  .page-about__fact-num {
    font-size: 28px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .page-about__guide-card,
  .page-about__branch,
  .page-about__timeline-item {
    transition: none;
  }
}