.page-about {
  --about-line: #6B6B6B;
  background: var(--bg-warm);
  color: var(--ink-normal);
  font-family: var(--font-body);
  line-height: 1.6;
}

.page-about__inner {
  max-width: var(--max-width);
  margin-inline: auto;
  position: relative;
  z-index: 1;
}

/* 面包屑 */
.page-about__breadcrumb {
  max-width: var(--max-width);
  margin-inline: auto;
  padding: 14px 20px 0;
  font-size: 12px;
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.page-about__breadcrumb-link {
  color: var(--ink-soft);
  text-decoration: none;
}
.page-about__breadcrumb-link + .page-about__breadcrumb-link::before {
  content: " / ";
  color: var(--line-grid);
  margin-right: 6px;
}
.page-about__breadcrumb-link[aria-current="page"] {
  color: var(--ink-normal);
  font-weight: 700;
}

/* Hero */
.page-about__hero {
  position: relative;
  padding: 36px 20px 40px;
  background: var(--bg-cool);
  border-bottom: 3px solid var(--ink-normal);
  overflow: hidden;
}
.page-about__hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(107,107,107,.14) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(107,107,107,.14) 1px, transparent 1px);
  background-size: 28px 28px;
  pointer-events: none;
}
.page-about__eyebrow {
  font-family: var(--font-tag);
  font-size: 13px;
  letter-spacing: .08em;
  color: var(--card-blue);
  margin: 0 0 6px;
  font-weight: 700;
}
.page-about__hero h1 {
  font-family: var(--font-heading);
  font-size: clamp(28px, 4vw, 44px);
  line-height: 1.15;
  margin: 0 0 12px;
  color: var(--ink-normal);
  letter-spacing: .01em;
}
.page-about__lead {
  font-size: 14px;
  max-width: 860px;
  color: var(--ink-soft);
  margin: 0 0 20px;
}
.page-about__hero-index {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}
.page-about__hero-index-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-heading);
  font-size: 15px;
  color: var(--ink-normal);
  text-decoration: none;
  border: 2px solid var(--ink-normal);
  padding: 8px 14px;
  transition: transform .15s, box-shadow .15s;
}
.page-about__hero-index-item--cn { background: var(--card-orange); }
.page-about__hero-index-item--jp { background: var(--card-blue); color: #fff; }
.page-about__hero-index-item--eu { background: var(--card-green); }
.page-about__hero-index-item--extra { background: var(--card-violet); color: #fff; }
.page-about__hero-index-item:hover {
  transform: translateY(-2px);
  box-shadow: 3px 3px 0 var(--ink-normal);
}

/* 通用 Section */
.page-about__section {
  padding: 48px 20px;
}
.page-about__section--warm {
  background: var(--bg-warm);
}
.page-about__section--cool {
  background: var(--bg-cool);
}
.page-about__section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
  border-bottom: 2px solid var(--ink-normal);
  padding-bottom: 10px;
  flex-wrap: wrap;
}
.page-about__section-head .section-title {
  font-family: var(--font-heading);
  font-size: 24px;
  margin: 0;
}
.page-about__section-code {
  font-family: var(--font-body);
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--ink-soft);
  background: var(--accent-yellow);
  border: 1px solid var(--ink-normal);
  padding: 2px 8px;
  white-space: nowrap;
}

/* 收录规模 */
.page-about__hero-image {
  display: block;
  width: 100%;
  height: auto;
  border: 2px solid var(--ink-normal);
  margin-bottom: 20px;
  background: var(--bg-warm);
}
.page-about__dashboard {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-bottom: 20px;
}
.page-about__stat {
  border: 2px solid var(--ink-normal);
  padding: 16px 12px;
  position: relative;
  text-align: center;
  box-shadow: 3px 3px 0 rgba(26,26,26,.15);
}
.page-about__stat--total { background: var(--card-orange); }
.page-about__stat--region { background: var(--card-blue); }
.page-about__stat--tag { background: var(--card-green); }
.page-about__stat--batch { background: var(--card-violet); }
.page-about__stat-num {
  display: block;
  font-family: var(--font-heading);
  font-size: 34px;
  line-height: 1.1;
  color: var(--ink-normal);
}
.page-about__stat--region .page-about__stat-num,
.page-about__stat--batch .page-about__stat-num {
  color: #fff;
}
.page-about__stat-label {
  display: block;
  font-family: var(--font-tag);
  font-size: 13px;
  margin-top: 4px;
  color: var(--ink-normal);
}
.page-about__stat-hint {
  display: block;
  font-size: 11px;
  margin-top: 6px;
  color: rgba(26,26,26,.72);
}
.page-about__stat--region .page-about__stat-label,
.page-about__stat--region .page-about__stat-hint,
.page-about__stat--batch .page-about__stat-label,
.page-about__stat--batch .page-about__stat-hint {
  color: rgba(255,255,255,.9);
}
.page-about__table-wrap {
  margin-bottom: 20px;
  overflow-x: auto;
  border: 2px solid var(--ink-normal);
  background: var(--bg-warm);
}
.page-about__table-wrap table {
  width: 100%;
  border-collapse: collapse;
  min-width: 560px;
}
.page-about__table-wrap th,
.page-about__table-wrap td {
  border: 1px solid var(--line-grid);
  padding: 10px 12px;
  text-align: left;
  font-size: 13px;
}
.page-about__table-wrap th {
  background: var(--bg-dark);
  color: var(--accent-yellow);
  font-family: var(--font-heading);
  font-weight: 400;
  letter-spacing: .04em;
  white-space: nowrap;
}
.page-about__table-wrap td:first-child {
  font-weight: 700;
}
.page-about__index-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}
.page-about__index-chip {
  background: var(--accent-yellow);
  border: 1px solid var(--ink-normal);
  font-family: var(--font-tag);
  font-size: 12px;
  padding: 4px 10px;
}

/* 站点定位 */
.page-about__split {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}
.page-about__definition h3 {
  font-family: var(--font-heading);
  font-size: 18px;
  margin: 0 0 10px;
}
.page-about__definition p {
  font-size: 14px;
  margin: 0 0 12px;
  color: var(--ink-soft);
}
.page-about__definition p:last-child {
  margin-bottom: 0;
}
.page-about__not-company {
  background: var(--accent-yellow);
  border: 2px solid var(--ink-normal);
  padding: 18px;
}
.page-about__not-company__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}
.page-about__not-company h3 {
  font-family: var(--font-heading);
  font-size: 18px;
  margin: 0;
}
.page-about__struct-icon {
  flex: 0 0 120px;
  width: 120px;
  height: 60px;
}
.page-about__not-list {
  margin: 0;
  padding-left: 18px;
  font-size: 13px;
}
.page-about__not-list li {
  margin: 4px 0;
}
.page-about__not-company__note {
  margin: 12px 0 0;
  font-size: 12px;
  border-top: 1px dashed var(--ink-normal);
  padding-top: 12px;
  color: var(--ink-soft);
}
.page-about__not-company__note a {
  color: var(--ink-normal);
  font-weight: 700;
}

/* 分类体系 */
.page-about__taxonomy-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}
.page-about__tree h3,
.page-about__tag-matrix h3 {
  font-family: var(--font-heading);
  font-size: 18px;
  margin: 0 0 14px;
}
.page-about__tree-root,
.page-about__tree-branches,
.page-about__tree-leaves {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about__tree-root-label {
  display: inline-block;
  background: var(--bg-dark);
  color: var(--accent-yellow);
  font-family: var(--font-heading);
  padding: 6px 14px;
  border: 2px solid var(--ink-normal);
}
.page-about__tree-branches {
  margin: 10px 0 0 14px;
  padding-left: 24px;
  border-left: 2px solid var(--line-grid);
}
.page-about__tree-branch {
  position: relative;
  padding: 8px 0;
}
.page-about__tree-branch::before {
  content: "";
  position: absolute;
  left: -24px;
  top: 22px;
  width: 18px;
  height: 2px;
  background: var(--line-grid);
}
.page-about__branch summary {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-heading);
  font-size: 16px;
  border: 2px solid var(--ink-normal);
  padding: 6px 10px;
  position: relative;
}
.page-about__branch summary::-webkit-details-marker {
  display: none;
}
.page-about__branch summary::after {
  content: "−";
  margin-left: auto;
  font-family: var(--font-body);
}
.page-about__branch:not([open]) summary::after {
  content: "+";
}
.page-about__branch-label--cn { background: var(--card-orange); }
.page-about__branch-label--jp { background: var(--card-blue); color: #fff; }
.page-about__branch-label--eu { background: var(--card-green); }
.page-about__branch-label--extra { background: var(--card-violet); color: #fff; }
.page-about__tree-leaves {
  margin: 10px 0 0 14px;
  padding-left: 24px;
  border-left: 2px dashed var(--line-grid);
}
.page-about__tree-leaf {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 6px 0;
  padding-left: 10px;
  position: relative;
}
.page-about__tree-leaf::before {
  content: "";
  position: absolute;
  left: -24px;
  top: 16px;
  width: 16px;
  height: 2px;
  background: var(--line-grid);
}
.page-about__tree-leaf-label {
  font-weight: 700;
  font-size: 13px;
  min-width: 100px;
}
.page-about__tree-leaf .status-badge {
  font-size: 11px;
  padding: 2px 6px;
}
.page-about__taxonomy-side {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.page-about__tag-matrix {
  background: var(--bg-cool);
  border: 2px solid var(--ink-normal);
  padding: 18px;
}
.page-about__tag-matrix .tag-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}
.page-about__tag-matrix p {
  font-size: 13px;
  margin: 0;
  color: var(--ink-soft);
}
.page-about__tree-image {
  display: block;
  width: 100%;
  height: auto;
  border: 2px solid var(--ink-normal);
}

/* 更新与反馈 */
.page-about__steps {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 0 auto 24px;
  padding: 0;
  max-width: 720px;
}
.page-about__step {
  flex: 1;
  background: var(--bg-warm);
  border: 2px solid var(--ink-normal);
  padding: 16px 18px;
  position: relative;
}
.page-about__step-num {
  display: inline-block;
  background: var(--accent-yellow);
  border: 1px solid var(--ink-normal);
  font-family: var(--font-heading);
  font-size: 20px;
  padding: 2px 8px;
  margin-bottom: 8px;
}
.page-about__step-title {
  display: block;
  font-family: var(--font-heading);
  font-size: 16px;
  margin-bottom: 4px;
}
.page-about__step-desc {
  display: block;
  font-size: 12px;
  color: var(--ink-soft);
}
.page-about__step-arrow {
  align-self: center;
  font-family: var(--font-heading);
  font-size: 22px;
  color: var(--card-blue);
  line-height: 1;
  display: inline-block;
  transform: rotate(90deg);
  width: 24px;
  height: 24px;
  text-align: center;
}
.page-about__cta-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
}

/* 底部纹理 */
.page-about__footer-texture {
  margin-top: 24px;
  padding: 20px 20px 0;
  opacity: .55;
}
.page-about__footer-texture img {
  display: block;
  max-width: 400px;
  width: 100%;
  height: auto;
  margin-left: auto;
  border: 0;
}

@media (min-width: 768px) {
  .page-about__hero {
    padding: 56px 40px 48px;
  }
  .page-about__hero h1 {
    font-size: 42px;
  }
  .page-about__lead {
    font-size: 15px;
  }
  .page-about__section {
    padding: 64px 40px;
  }
  .page-about__dashboard {
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
  }
  .page-about__stat-num {
    font-size: 44px;
  }
  .page-about__split {
    grid-template-columns: 1fr 1fr;
    gap: 40px;
  }
  .page-about__taxonomy-layout {
    grid-template-columns: 1.15fr .85fr;
    gap: 40px;
  }
  .page-about__steps {
    flex-direction: row;
    align-items: stretch;
    max-width: none;
    gap: 8px;
  }
  .page-about__step-arrow {
    transform: none;
    align-self: center;
  }
  .page-about__footer-texture {
    padding: 32px 40px 0;
  }
}