.page-about {
  --about-white: #FFFFFF;
  --about-line: #EADACE;
  --about-coral-soft: #FFF3EC;
  --about-teal-soft: #E2F3EF;
  --about-lemon-soft: #FBF6D9;
  --about-muted: #4A4E69;
  --about-ink: #1D1E2C;
  background: var(--page-bg);
  color: var(--text-primary);
  font-family: var(--font-body);
  line-height: 1.75;
  overflow-x: hidden;
}

.page-about *,
.page-about *::before,
.page-about *::after {
  box-sizing: border-box;
}

.page-about .container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 24px 16px 64px;
}

.page-about .breadcrumbs {
  margin-bottom: 20px;
  font-size: 13px;
}

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

.page-about figure {
  margin: 0;
}

.page-about .sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  overflow: hidden;
  white-space: nowrap;
  border: 0;
}

/* ============ 首屏 Hero ============ */
.page-about .about-hero {
  position: relative;
  margin-bottom: 28px;
  padding: 32px 22px;
  border-radius: var(--radius-large);
  background:
    radial-gradient(circle at 92% 18%, var(--card-lemon) 0 9%, transparent 9.5%),
    radial-gradient(circle at 84% 42%, var(--card-teal) 0 5%, transparent 5.5%),
    var(--section-bg-1);
  overflow: hidden;
}

.page-about .about-hero__rail {
  display: none;
}

.page-about .about-hero__kicker {
  display: inline-block;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--primary-color);
  background: var(--about-white);
  padding: 3px 14px;
  border-radius: var(--radius-pill);
  margin-bottom: 14px;
}

.page-about .about-hero h1 {
  margin: 0 0 10px;
  font-family: var(--font-heading);
  font-size: 24px;
  line-height: 1.35;
  color: var(--text-primary);
}

.page-about .about-hero__desc {
  font-size: 14px;
  color: var(--text-secondary);
  margin: 0 0 18px;
}

.page-about .about-hero__stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}

.page-about .hero-stat {
  background: var(--about-white);
  padding: 10px 12px;
  border-radius: var(--radius-medium);
  border-left: 5px solid transparent;
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
}

.page-about .hero-stat--coral {
  border-left-color: var(--card-coral);
}

.page-about .hero-stat--teal {
  border-left-color: var(--card-teal);
}

.page-about .hero-stat--lemon {
  border-left-color: var(--card-lemon);
}

.page-about .hero-stat--accent {
  border-left-color: var(--accent-color);
}

.page-about .hero-stat__num {
  font-family: var(--font-heading);
  font-size: 22px;
  font-weight: 700;
  line-height: 1.25;
  color: var(--about-ink);
}

.page-about .hero-stat__label {
  font-size: 12px;
  color: var(--text-secondary);
  line-height: 1.4;
}

/* ============ 章节通用结构 ============ */
.page-about .about-section {
  margin: 0 0 28px;
  padding: 26px 20px;
  border-radius: var(--radius-large);
  background: var(--about-white);
  box-shadow: var(--shadow-card);
}

.page-about .about-section__rail {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
}

.page-about .section-num {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 14px;
  font-weight: 700;
  background: var(--primary-color);
  color: #fff;
  border-radius: var(--radius-pill);
  padding: 2px 14px;
  line-height: 1.6;
  letter-spacing: 0.04em;
}

.page-about .section-name {
  font-family: var(--font-heading);
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
}

.page-about .section-heading {
  margin-bottom: 18px;
}

.page-about .section-kicker {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.16em;
  color: var(--primary-color);
  background: var(--about-coral-soft);
  border-radius: var(--radius-pill);
  padding: 2px 12px;
  margin-bottom: 8px;
}

.page-about .section-heading h2 {
  margin: 0 0 8px;
  font-family: var(--font-heading);
  font-size: 20px;
  line-height: 1.4;
  color: var(--about-ink);
}

.page-about .section-desc {
  margin: 0;
  font-size: 14px;
  color: var(--about-muted);
  max-width: 720px;
}

.page-about .section-position {
  background: var(--section-bg-1);
}

.page-about .section-scope {
  background: var(--section-bg-2);
}

.page-about .section-taxonomy {
  background: var(--section-bg-3);
}

.page-about .section-update {
  background: var(--about-white);
}

.page-about .section-retrieve {
  background: var(--section-bg-1);
}

.page-about .section-help {
  background: var(--about-white);
}

/* ============ 01 站点定位 ============ */
.page-about .position-layout {
  display: grid;
  gap: 20px;
}

.page-about .position-media {
  margin: 0;
  border-radius: var(--radius-medium);
  overflow: hidden;
  background: var(--about-lemon-soft);
}

.page-about .position-media img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .position-media figcaption {
  font-size: 12px;
  color: var(--text-secondary);
  text-align: center;
  padding: 10px 12px;
  background: var(--about-white);
}

.page-about .position-cards {
  display: grid;
  gap: 14px;
}

.page-about .position-card {
  background: var(--about-white);
  border-radius: var(--radius-medium);
  padding: 18px 20px;
  border-left: 6px solid transparent;
  box-shadow: var(--shadow-card);
}

.page-about .position-card--coral {
  border-left-color: var(--card-coral);
}

.page-about .position-card--teal {
  border-left-color: var(--card-teal);
}

.page-about .position-card--lemon {
  border-left-color: var(--card-lemon);
}

.page-about .position-card__badge {
  display: inline-block;
  font-size: 12px;
  font-family: var(--font-heading);
  font-weight: 700;
  background: var(--primary-color);
  color: #fff;
  padding: 1px 14px;
  border-radius: var(--radius-pill);
  margin-bottom: 8px;
}

.page-about .position-card--teal .position-card__badge {
  background: var(--card-teal);
}

.page-about .position-card--lemon .position-card__badge {
  background: var(--card-lemon);
  color: var(--about-ink);
}

.page-about .position-card h3 {
  margin: 0 0 6px;
  font-family: var(--font-heading);
  font-size: 16px;
  color: var(--about-ink);
}

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

/* ============ 02 收录范围 ============ */
.page-about .scope-layout {
  display: grid;
  gap: 20px;
}

.page-about .scope-media {
  margin: 0;
  border-radius: var(--radius-medium);
  overflow: hidden;
  background: var(--about-teal-soft);
}

.page-about .scope-media img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .scope-media figcaption {
  font-size: 12px;
  color: var(--text-secondary);
  text-align: center;
  padding: 10px 12px;
  background: var(--about-white);
}

.page-about .scope-table-wrap {
  overflow-x: auto;
  border-radius: var(--radius-medium);
  background: var(--about-white);
  box-shadow: var(--shadow-card);
}

.page-about .scope-table {
  width: 100%;
  min-width: 340px;
  border-collapse: collapse;
  font-size: 14px;
}

.page-about .scope-table th {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 13px;
  background: var(--about-ink);
  color: #fff;
  padding: 10px 14px;
  text-align: left;
  letter-spacing: 0.04em;
}

.page-about .scope-table td {
  padding: 9px 14px;
  border-bottom: 1px solid var(--border-light);
  color: var(--about-ink);
}

.page-about .scope-table tbody tr:hover {
  background: var(--about-coral-soft);
}

.page-about .scope-table tbody tr:last-child td {
  border-bottom: none;
}

.page-about .scope-table td:first-child::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  margin-right: 10px;
  vertical-align: middle;
  background: var(--card-coral);
}

.page-about .scope-table tbody tr:nth-child(3n+1) td:first-child::before {
  background: var(--card-coral);
}

.page-about .scope-table tbody tr:nth-child(3n+2) td:first-child::before {
  background: var(--card-teal);
}

.page-about .scope-table tbody tr:nth-child(3n+3) td:first-child::before {
  background: var(--card-lemon);
}

.page-about .scope-table .scope-table__total td {
  font-weight: 700;
  background: var(--about-lemon-soft);
  border-top: 2px solid var(--card-lemon);
}

.page-about .scope-note {
  margin: 16px 0 0;
  font-size: 14px;
  color: var(--about-muted);
}

.page-about .about-link {
  color: var(--accent-color);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ============ 03 分类体系 ============ */
.page-about .taxonomy-layout {
  display: grid;
  gap: 20px;
}

.page-about .taxonomy-media {
  margin: 0;
  border-radius: var(--radius-medium);
  overflow: hidden;
  background: var(--about-coral-soft);
}

.page-about .taxonomy-media img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .taxonomy-media figcaption {
  font-size: 12px;
  color: var(--text-secondary);
  text-align: center;
  padding: 10px 12px;
  background: var(--about-white);
}

.page-about .taxonomy-flow {
  display: grid;
  gap: 14px;
}

.page-about .taxonomy-stage {
  background: var(--about-white);
  border-radius: var(--radius-medium);
  box-shadow: var(--shadow-card);
  padding: 18px;
  border-top: 5px solid transparent;
}

.page-about .taxonomy-stage--coral {
  border-top-color: var(--card-coral);
}

.page-about .taxonomy-stage--lemon {
  border-top-color: var(--card-lemon);
}

.page-about .taxonomy-stage--teal {
  border-top-color: var(--card-teal);
}

.page-about .taxonomy-stage__title {
  display: block;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 15px;
  color: var(--about-ink);
}

.page-about .taxonomy-stage__count {
  display: inline-block;
  margin-top: 2px;
  font-size: 12px;
  color: var(--primary-color);
  background: var(--about-coral-soft);
  padding: 1px 12px;
  border-radius: var(--radius-pill);
}

.page-about .taxonomy-stage--lemon .taxonomy-stage__count {
  color: #4D4100;
  background: var(--about-lemon-soft);
}

.page-about .taxonomy-stage--teal .taxonomy-stage__count {
  color: #14534D;
  background: var(--about-teal-soft);
}

.page-about .taxonomy-stage__desc {
  margin: 10px 0 0;
  font-size: 13px;
  color: var(--about-muted);
}

.page-about .taxonomy-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 12px;
}

.page-about .taxonomy-pill {
  font-size: 12px;
  padding: 2px 12px;
  border-radius: var(--radius-pill);
  border: 1.5px solid var(--card-coral);
  background: var(--about-coral-soft);
  color: #7A3419;
}

.page-about .taxonomy-pill:nth-child(3n+2) {
  border-color: var(--card-teal);
  background: var(--about-teal-soft);
  color: #14534D;
}

.page-about .taxonomy-pill:nth-child(3n+3) {
  border-color: var(--card-lemon);
  background: var(--about-lemon-soft);
  color: #4D4100;
}

.page-about .taxonomy-flow__arrow {
  font-size: 24px;
  font-weight: 700;
  color: var(--primary-color);
  text-align: center;
  transform: rotate(90deg);
  line-height: 1;
}

.page-about .taxonomy-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 12px;
}

.page-about .taxonomy-tag {
  font-size: 12px;
  padding: 4px 14px;
  border-radius: var(--radius-pill);
  font-family: var(--font-heading);
}

.page-about .taxonomy-tag--tone {
  background: var(--card-lemon);
  color: #4D4100;
}

.page-about .taxonomy-tag--style {
  background: var(--card-teal);
  color: #0C3E3A;
}

/* ============ 04 更新机制 ============ */
.page-about .update-grid {
  display: grid;
  gap: 20px;
}

.page-about .update-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .timeline-item {
  position: relative;
  padding: 0 0 24px 26px;
  border-left: 3px solid var(--border-light);
}

.page-about .timeline-item:last-child {
  border-left-color: transparent;
  padding-bottom: 0;
}

.page-about .timeline-dot {
  position: absolute;
  left: -8px;
  top: 2px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  border: 3px solid var(--page-bg);
}

.page-about .timeline-dot--coral {
  background: var(--card-coral);
}

.page-about .timeline-dot--lemon {
  background: var(--card-lemon);
}

.page-about .timeline-dot--teal {
  background: var(--card-teal);
}

.page-about .timeline-dot--primary {
  background: var(--primary-color);
}

.page-about .timeline-content {
  display: grid;
  gap: 2px;
}

.page-about .timeline-label {
  font-size: 12px;
  color: var(--text-secondary);
  letter-spacing: 0.08em;
}

.page-about .timeline-value {
  font-family: var(--font-heading);
  font-size: 16px;
  color: var(--about-ink);
}

.page-about .timeline-desc {
  margin: 4px 0 0;
  font-size: 13px;
  color: var(--about-muted);
}

.page-about .update-aside__card {
  background: var(--section-bg-3);
  border-radius: var(--radius-large);
  padding: 24px;
  box-shadow: var(--shadow-card);
}

.page-about .update-aside__title {
  display: block;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 20px;
  margin-bottom: 14px;
  color: var(--about-ink);
}

.page-about .update-aside__row {
  display: flex;
  justify-content: space-between;
  padding: 10px 0;
  border-bottom: 1px dashed #C9DACF;
  font-size: 14px;
  color: var(--about-ink);
}

.page-about .update-aside__row--total {
  border-bottom: none;
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 18px;
  color: var(--primary-color);
}

.page-about .update-aside__note {
  margin-top: 10px;
  font-size: 12px;
  color: var(--text-secondary);
}

/* ============ 05 检索与适配 ============ */
.page-about .retrieve-grid {
  display: grid;
  gap: 16px;
}

.page-about .retrieve-card {
  background: var(--about-white);
  border-radius: var(--radius-medium);
  box-shadow: var(--shadow-card);
  padding: 22px;
}

.page-about .retrieve-card h3 {
  margin: 0 0 10px;
  font-family: var(--font-heading);
  font-size: 17px;
  color: var(--about-ink);
}

.page-about .retrieve-list {
  list-style: none;
  margin: 0 0 12px;
  padding: 0;
}

.page-about .retrieve-list li {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px dashed var(--border-light);
  font-size: 15px;
  color: var(--about-ink);
}

.page-about .retrieve-index {
  flex: 0 0 30px;
  display: inline-block;
  text-align: center;
  background: var(--about-ink);
  color: #fff;
  font-family: var(--font-heading);
  font-weight: 700;
  border-radius: var(--radius-pill);
  padding: 2px 0;
  font-size: 12px;
}

.page-about .retrieve-check {
  flex: 0 0 30px;
  display: inline-block;
  text-align: center;
  background: var(--card-teal);
  color: #fff;
  border-radius: var(--radius-pill);
  font-size: 14px;
  font-weight: 700;
  padding: 2px 0;
}

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

.page-about .retrieve-indexbar {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  justify-content: center;
  margin-top: 24px;
}

.page-about .retrieve-indexbar span {
  width: 26px;
  height: 26px;
  display: grid;
  place-items: center;
  font-size: 11px;
  border-radius: 9px;
  background: #F3E9D8;
  color: #6E5A44;
  font-family: var(--font-heading);
  font-weight: 700;
}

.page-about .retrieve-indexbar span:nth-child(3n+1) {
  background: #FFE8DD;
  color: #9B4B28;
}

.page-about .retrieve-indexbar span:nth-child(3n+2) {
  background: #E2F3EF;
  color: #14685F;
}

.page-about .retrieve-indexbar span:nth-child(3n+3) {
  background: #F7EFC8;
  color: #6B5A12;
}

/* ============ 06 使用帮助 ============ */
.page-about .help-accordion {
  display: grid;
  gap: 12px;
}

.page-about .help-item {
  background: var(--about-white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-medium);
  overflow: hidden;
  box-shadow: var(--shadow-card);
}

.page-about .help-item summary {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  padding: 16px 20px;
  cursor: pointer;
  font-family: var(--font-heading);
  font-size: 15px;
  font-weight: 600;
  color: var(--about-ink);
  list-style: none;
}

.page-about .help-item summary::-webkit-details-marker {
  display: none;
}

.page-about .help-item__arrow {
  transition: transform 0.25s ease;
  color: var(--primary-color);
  font-size: 18px;
  line-height: 1;
}

.page-about .help-item[open] .help-item__arrow {
  transform: rotate(180deg);
}

.page-about .help-item__body {
  padding: 0 20px 18px;
  font-size: 14px;
  color: var(--about-muted);
}

.page-about .help-item__body p {
  margin: 0;
}

.page-about .help-more {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.page-about .about-link {
  font-weight: 700;
}

/* ============ 平板与桌面 ============ */
@media (min-width: 768px) {
  .page-about .container {
    padding: 32px 32px 80px;
  }

  .page-about .about-hero {
    display: grid;
    grid-template-columns: 140px 1fr;
    gap: 24px;
    padding: 44px;
  }

  .page-about .about-hero__rail {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 8px;
    padding-left: 16px;
    border-left: 3px solid var(--primary-color);
  }

  .page-about .about-hero__en {
    writing-mode: vertical-rl;
    font-family: var(--font-heading);
    font-weight: 700;
    letter-spacing: 0.24em;
    color: var(--primary-color);
    font-size: 14px;
    padding-bottom: 30px;
  }

  .page-about .about-hero__cn {
    writing-mode: vertical-rl;
    font-family: var(--font-heading);
    font-weight: 700;
    letter-spacing: 0.2em;
    color: var(--text-primary);
    font-size: 16px;
  }

  .page-about .about-hero h1 {
    font-size: 30px;
  }

  .page-about .about-hero__desc {
    font-size: 15px;
  }

  .page-about .about-hero__stats {
    grid-template-columns: repeat(4, 1fr);
  }

  .page-about .about-section {
    display: grid;
    grid-template-columns: 110px 1fr;
    gap: 28px;
    padding: 36px;
  }

  .page-about .about-section__rail {
    flex-direction: column;
    align-items: flex-end;
    margin-bottom: 0;
    padding-top: 6px;
  }

  .page-about .section-name {
    writing-mode: vertical-rl;
    font-size: 16px;
  }

  .page-about .section-heading h2 {
    font-size: 24px;
  }
}

@media (min-width: 1000px) {
  .page-about .position-layout {
    grid-template-columns: 2fr 3fr;
    align-items: center;
    gap: 28px;
  }

  .page-about .scope-layout {
    grid-template-columns: 5fr 7fr;
    align-items: center;
    gap: 28px;
  }

  .page-about .taxonomy-layout {
    grid-template-columns: 5fr 7fr;
    align-items: center;
    gap: 28px;
  }

  .page-about .taxonomy-flow {
    grid-template-columns: 1fr auto 1fr auto 1fr;
    align-items: center;
    gap: 12px;
  }

  .page-about .taxonomy-flow__arrow {
    transform: none;
  }

  .page-about .update-grid {
    grid-template-columns: 3fr 2fr;
    align-items: start;
    gap: 28px;
  }

  .page-about .retrieve-grid {
    grid-template-columns: 1fr 1fr;
    gap: 20px;
  }
}