.page-about {
  --about-sidebar-w: 224px;
  --about-panel-bg: #0E1E30;
  --about-card-bg: #16293F;
  --about-border-soft: rgba(41, 68, 96, 0.6);
  padding: var(--space-md) 0 var(--space-2xl);
}

/* 面包屑 */
.page-about .breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  margin-bottom: var(--space-lg);
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--color-text-dim);
}

.page-about .breadcrumb a {
  text-decoration: none;
  color: var(--color-accent-blue);
  transition: color var(--transition-fast);
}

.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  color: var(--color-accent-green);
  outline: none;
}

/* 页面头部 */
.page-about .about-hero {
  position: relative;
  padding: var(--space-lg) 0 var(--space-xl);
  margin-bottom: var(--space-xl);
  border-bottom: 1px solid var(--color-border-fine);
  background-image:
    linear-gradient(rgba(60, 140, 255, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(60, 140, 255, 0.05) 1px, transparent 1px);
  background-size: 26px 26px;
}

.page-about .about-hero::before {
  content: '';
  position: absolute;
  left: 0;
  top: var(--space-md);
  bottom: var(--space-md);
  width: 3px;
  border-radius: 2px;
  background: linear-gradient(180deg, var(--color-accent-green), var(--color-accent-blue));
}

.page-about .about-hero__tag {
  display: inline-block;
  margin-bottom: var(--space-md);
  padding: 4px 10px;
  border: 1px solid var(--color-border-fine);
  border-radius: var(--radius-sm);
  background: rgba(183, 245, 66, 0.06);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.05em;
  color: var(--color-accent-green);
}

.page-about .about-hero__title {
  margin: 0 0 var(--space-sm);
  max-width: 640px;
  font-size: clamp(28px, 4vw, 42px);
  line-height: 1.18;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--color-text-bright);
}

.page-about .about-hero__lead {
  margin: 0;
  max-width: 640px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-text-dim);
}

/* 主体布局：移动端单列 */
.page-about .about-layout {
  display: block;
}

.page-about .about-main {
  display: flex;
  flex-direction: column;
  gap: var(--space-xl);
}

/* 章节面板 */
.page-about .about-panel {
  padding: var(--space-lg);
  background: var(--about-panel-bg);
  border: 1px solid var(--color-border-fine);
  border-radius: 6px;
  box-shadow: var(--panel-shadow);
  transition: border-color var(--transition-fast), transform var(--transition-fast);
}

.page-about .about-panel:hover {
  border-color: var(--color-accent-green);
  transform: translateY(-2px);
}

.page-about .about-panel:focus-within {
  border-color: var(--color-accent-orange);
}

.page-about .about-panel__head {
  display: flex;
  align-items: baseline;
  gap: var(--space-sm);
  margin-bottom: var(--space-xs);
}

.page-about .about-panel__index {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--color-accent-orange);
  white-space: nowrap;
}

.page-about .about-panel__title {
  margin: 0;
  font-size: 22px;
  font-weight: 700;
  line-height: 1.3;
  color: var(--color-text-bright);
}

.page-about .about-panel__lead {
  margin: 0 0 var(--space-md);
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-dim);
  border-left: 2px solid var(--color-accent-blue);
  padding-left: var(--space-sm);
}

.page-about .about-panel__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  margin-top: var(--space-md);
}

/* 01 品牌站定位 */
.page-about .about-positioning-content > p {
  margin: 0 0 var(--space-md);
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-text-dim);
}

.page-about .about-fact-list {
  margin: 0 0 var(--space-md);
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--color-border-fine);
}

.page-about .about-fact-list li {
  position: relative;
  padding: var(--space-sm) 0 var(--space-sm) 20px;
  border-bottom: 1px solid var(--color-border-fine);
  font-size: 14px;
  line-height: 1.65;
  color: var(--color-text-bright);
}

.page-about .about-fact-list li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 21px;
  width: 8px;
  height: 8px;
  border-radius: 1px;
  background: var(--color-accent-green);
  transform: rotate(45deg);
}

.page-about .about-modules {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
}

.page-about .about-module-card {
  padding: var(--space-sm);
  background: var(--about-card-bg);
  border: 1px solid var(--about-border-soft);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast), transform var(--transition-fast);
}

.page-about .about-module-card:hover {
  border-color: var(--color-accent-green);
  transform: translateY(-2px);
}

.page-about .about-module-card__index {
  display: inline-block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--color-data-cyan);
}

.page-about .about-module-card h3 {
  margin: 0 0 4px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text-bright);
}

.page-about .about-module-card p {
  margin: 0;
  font-size: 12px;
  line-height: 1.55;
  color: var(--color-text-dim);
}

/* 02 数据服务原则 */
.page-about .about-data-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-lg);
}

.page-about .about-data-visual img,
.page-about .about-timeline-img img,
.page-about .about-feedback-card img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--color-border-fine);
  border-radius: var(--radius-md);
  object-fit: cover;
}

.page-about .about-data-content {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.page-about .about-principle {
  display: flex;
  gap: var(--space-sm);
  padding: var(--space-sm);
  background: var(--about-card-bg);
  border: 1px solid var(--about-border-soft);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast);
}

.page-about .about-principle:hover {
  border-color: var(--color-accent-blue);
}

.page-about .about-principle__num {
  flex-shrink: 0;
  padding-top: 2px;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--color-data-cyan);
}

.page-about .about-principle h3 {
  margin: 0 0 4px;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text-bright);
}

.page-about .about-principle p {
  margin: 0;
  font-size: 13px;
  line-height: 1.65;
  color: var(--color-text-dim);
}

/* 03 V4 导航发展轨迹 */
.page-about .about-timeline-img {
  margin-bottom: var(--space-lg);
}

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

.page-about .about-timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 9px;
  bottom: 9px;
  width: 1px;
  background: var(--color-border-fine);
}

.page-about .about-timeline__item {
  position: relative;
  padding: 0 0 var(--space-lg) 32px;
}

.page-about .about-timeline__item:last-child {
  padding-bottom: 0;
}

.page-about .about-timeline__node {
  position: absolute;
  left: 0;
  top: 6px;
  width: 15px;
  height: 15px;
  border: 3px solid var(--color-bg-deep);
  border-radius: 50%;
  background: var(--color-accent-green);
  box-shadow: 0 0 0 1px var(--color-accent-green);
  transition: transform var(--transition-fast);
}

.page-about .about-timeline__item:hover .about-timeline__node {
  transform: scale(1.2);
}

.page-about .about-timeline__card {
  padding: var(--space-sm) var(--space-md);
  background: var(--about-card-bg);
  border: 1px solid var(--about-border-soft);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast), transform var(--transition-fast);
}

.page-about .about-timeline__item:hover .about-timeline__card {
  border-color: var(--color-accent-green);
  transform: translateY(-2px);
}

.page-about .about-timeline__ver {
  display: inline-block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--color-accent-blue);
}

.page-about .about-timeline__card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.65;
  color: var(--color-text-dim);
}

/* 版本展开 */
.page-about .about-details {
  margin-top: var(--space-lg);
  border: 1px solid var(--color-border-fine);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition-fast);
}

.page-about .about-details:hover {
  border-color: var(--color-accent-green);
}

.page-about .about-details summary {
  cursor: pointer;
  padding: var(--space-sm) var(--space-md);
  font-size: 14px;
  color: var(--color-text-bright);
  background: var(--about-card-bg);
  list-style: none;
  user-select: none;
  transition: background var(--transition-fast);
}

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

.page-about .about-details summary::before {
  content: '＋';
  display: inline-block;
  width: 18px;
  font-family: var(--font-mono);
  color: var(--color-accent-green);
}

.page-about .about-details[open] summary::before {
  content: '－';
}

.page-about .about-details summary:hover {
  background: var(--color-bg-panel);
}

.page-about .about-details summary:focus-visible {
  outline: 2px solid var(--color-accent-orange);
  outline-offset: -2px;
}

.page-about .about-details__body {
  padding: var(--space-sm) var(--space-md) var(--space-md);
  border-top: 1px solid var(--color-border-fine);
}

.page-about .about-details__body p {
  margin: 0 0 var(--space-sm);
  font-size: 13px;
  line-height: 1.75;
  color: var(--color-text-dim);
}

.page-about .about-details__body p:last-child {
  margin-bottom: 0;
}

/* 04 用户与反馈体系 */
.page-about .about-feedback-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-lg);
}

.page-about .about-feedback-card {
  align-self: start;
}

.page-about .about-feedback-info > p {
  margin: 0 0 var(--space-md);
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-text-dim);
}

.page-about .about-contact-list {
  margin: 0 0 var(--space-md);
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--color-border-fine);
}

.page-about .about-contact-list li {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: var(--space-sm) 0;
  border-bottom: 1px solid var(--color-border-fine);
}

.page-about .about-contact-list__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--color-accent-orange);
}

.page-about .about-contact-list__value {
  font-size: 14px;
  line-height: 1.55;
  color: var(--color-text-bright);
  word-break: break-all;
}

.page-about a.about-contact-list__value {
  color: var(--color-accent-blue);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.page-about a.about-contact-list__value:hover {
  color: var(--color-accent-green);
  text-decoration: underline;
}

.page-about .about-feedback-steps {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  margin-bottom: var(--space-md);
}

.page-about .about-feedback-step {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-sm);
  background: var(--about-card-bg);
  border: 1px solid var(--about-border-soft);
  border-radius: var(--radius-sm);
}

.page-about .about-feedback-step__num {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-bg-deep);
  background: var(--color-accent-green);
}

.page-about .about-feedback-step p {
  margin: 0;
  font-size: 13px;
  line-height: 1.55;
  color: var(--color-text-dim);
}

.page-about .about-feedback-note {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-sm);
}

/* 侧边栏 */
.page-about .about-sidebar {
  display: none;
}

/* 焦点可见轮廓 */
.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--color-accent-orange);
  outline-offset: 2px;
}

/* 桌面端 */
@media (min-width: 768px) {
  .page-about .about-modules {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .about-data-grid {
    grid-template-columns: minmax(0, 260px) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-feedback-wrap {
    grid-template-columns: minmax(0, 300px) minmax(0, 1fr);
    align-items: start;
  }
}

@media (min-width: 1024px) {
  .page-about .about-layout {
    display: grid;
    grid-template-columns: minmax(0, 1fr) var(--about-sidebar-w);
    gap: var(--space-2xl);
    align-items: start;
  }

  .page-about .about-sidebar {
    display: block;
    position: sticky;
    top: var(--space-md);
    align-self: start;
  }

  .page-about .about-sidenav {
    padding: var(--space-md);
    background: var(--about-panel-bg);
    border: 1px solid var(--color-border-fine);
    border-radius: var(--radius-md);
    box-shadow: var(--panel-shadow);
    transition: border-color var(--transition-fast);
  }

  .page-about .about-sidenav:hover {
    border-color: var(--color-accent-blue);
  }

  .page-about .about-sidenav__label {
    display: block;
    margin-bottom: var(--space-sm);
    font-family: var(--font-mono);
    font-size: 12px;
    letter-spacing: 0.08em;
    color: var(--color-accent-orange);
  }

  .page-about .about-sidenav__list {
    margin: 0 0 var(--space-sm);
    padding: 0;
    list-style: none;
  }

  .page-about .about-sidenav__link {
    display: block;
    padding: 9px 0;
    font-family: var(--font-mono);
    font-size: 12px;
    line-height: 1.4;
    color: var(--color-text-dim);
    text-decoration: none;
    border-bottom: 1px solid rgba(41, 68, 96, 0.35);
    transition: color var(--transition-fast), padding-left var(--transition-fast);
  }

  .page-about .about-sidenav__list li:last-child .about-sidenav__link {
    border-bottom: none;
  }

  .page-about .about-sidenav__link:hover {
    color: var(--color-text-bright);
    padding-left: 4px;
  }

  .page-about .about-sidenav__link.is-active {
    color: var(--color-accent-green);
    padding-left: 4px;
  }

  .page-about .about-sidenav__status {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    padding-top: var(--space-sm);
    border-top: 1px solid var(--color-border-fine);
    font-size: 12px;
    line-height: 1.5;
    color: var(--color-text-dim);
  }

  .page-about .about-sidenav__dot {
    flex-shrink: 0;
    width: 8px;
    height: 8px;
    margin-top: 4px;
    border-radius: 50%;
    background: var(--color-accent-green);
    box-shadow: 0 0 8px rgba(183, 245, 66, 0.6);
  }
}