.page-about {
  --about-gap: var(--spacing-xl);
  --about-radius: var(--radius-md);
  --about-timeline-color: var(--color-accent);
  --about-mission-bg: rgba(255, 255, 255, 0.03);
  --about-mission-border: var(--color-primary);
  --about-card-bg: var(--color-surface);
  --about-card-hover: var(--color-surface-hover);
  --about-service-transition: var(--transition-base);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
  padding: calc(var(--header-height) + var(--spacing-xl)) var(--spacing-md) var(--spacing-2xl);
  max-width: var(--max-width);
  margin: 0 auto;
  width: 100%;
  box-sizing: border-box;
}

/* 面包屑 */
.page-about .breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-family: var(--font-body);
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-sm);
}

.page-about .breadcrumb-link {
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.page-about .breadcrumb-link:hover {
  color: var(--color-accent);
}

.page-about .breadcrumb-sep {
  color: var(--color-border);
  font-size: 0.75rem;
}

.page-about .breadcrumb-current {
  color: var(--color-text-primary);
  font-weight: 500;
}

/* 页面头部 */
.page-about .about-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: var(--spacing-md);
  padding: var(--spacing-lg) 0 var(--spacing-xl);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--spacing-sm);
}

.page-about .about-brandmark {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: var(--color-surface);
  object-fit: cover;
  box-shadow: 0 0 0 3px var(--color-accent);
  transition: transform var(--transition-fast);
}

.page-about .about-brandmark:hover {
  transform: scale(1.03);
}

.page-about .about-headline {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  color: var(--color-text-primary);
  line-height: 1.15;
  margin: 0;
  letter-spacing: -0.01em;
}

.page-about .about-subtitle {
  font-family: var(--font-body);
  font-size: clamp(1rem, 2.2vw, 1.2rem);
  color: var(--color-text-secondary);
  max-width: 600px;
  line-height: 1.5;
  margin: 0;
}

/* 两列布局 */
.page-about .about-layout {
  display: flex;
  flex-direction: column;
  gap: var(--about-gap);
}

/* 左栏 - 使命 */
.page-about .about-mission {
  background: var(--about-mission-bg);
  border-left: 4px solid var(--about-mission-border);
  border-radius: 0 var(--about-radius) var(--about-radius) 0;
  padding: var(--spacing-lg) var(--spacing-xl);
  flex-shrink: 0;
}

.page-about .mission-heading {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-primary);
  margin: 0 0 var(--spacing-md);
  line-height: 1.2;
}

.page-about .mission-text {
  font-family: var(--font-body);
  font-size: 1rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin: 0 0 var(--spacing-lg);
}

.page-about .mission-quote {
  margin: 0;
  padding: var(--spacing-sm) var(--spacing-md);
  border-top: 1px solid var(--color-border);
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-style: italic;
  color: var(--color-text-primary);
  line-height: 1.6;
  position: relative;
}

.page-about .quote-mark {
  color: var(--color-accent);
  font-size: 1.6rem;
  line-height: 0;
  vertical-align: -0.25em;
}

/* 右栏 - 内容区 */
.page-about .about-content {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-2xl);
  flex: 1;
  min-width: 0;
}

.page-about .block-title {
  font-family: var(--font-heading);
  font-size: 1.75rem;
  font-weight: 600;
  color: var(--color-text-primary);
  margin: 0 0 var(--spacing-lg);
  line-height: 1.2;
  position: relative;
  display: inline-block;
}

.page-about .block-title::after {
  content: '';
  display: block;
  width: 60%;
  height: 3px;
  background: var(--color-primary);
  border-radius: 2px;
  margin-top: var(--spacing-xs);
}

/* 服务卡片网格 */
.page-about .services-grid {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

/* 服务卡片 - 使用 details/summary 实现点击展开 */
.page-about .service-card {
  background: var(--about-card-bg);
  border-radius: var(--about-radius);
  border: 1px solid var(--color-border);
  overflow: hidden;
  transition: border-color var(--about-service-transition), background var(--about-service-transition);
}

.page-about .service-card[open] {
  border-color: var(--color-accent);
  background: var(--about-card-hover);
}

.page-about .service-summary {
  list-style: none;
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md) var(--spacing-lg);
  cursor: pointer;
  user-select: none;
  transition: background var(--transition-fast);
}

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

.page-about .service-summary:hover {
  background: rgba(255, 255, 255, 0.04);
}

.page-about .service-icon {
  flex-shrink: 0;
  color: var(--color-primary);
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color var(--transition-fast);
}

.page-about .service-card[open] .service-icon {
  color: var(--color-accent);
}

.page-about .service-label {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.page-about .service-name {
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text-primary);
  transition: color var(--transition-fast);
}

.page-about .service-card[open] .service-name {
  color: var(--color-accent);
}

.page-about .service-brief {
  font-family: var(--font-body);
  font-size: 0.85rem;
  color: var(--color-text-secondary);
}

.page-about .service-toggle {
  flex-shrink: 0;
  font-size: 1.4rem;
  font-weight: 300;
  color: var(--color-text-secondary);
  transition: transform var(--about-service-transition), color var(--about-service-transition);
  line-height: 1;
}

.page-about .service-card[open] .service-toggle {
  transform: rotate(45deg);
  color: var(--color-accent);
}

.page-about .service-detail {
  padding: 0 var(--spacing-lg) var(--spacing-lg);
  font-family: var(--font-body);
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
  border-top: 1px solid var(--color-border);
  margin-top: 0;
  padding-top: var(--spacing-md);
}

.page-about .service-detail p {
  margin: 0 0 var(--spacing-sm);
}

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

.page-about .service-img {
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-sm);
  margin-top: var(--spacing-sm);
  object-fit: cover;
  background: var(--color-bg);
}

/* 时间线 - 版本更新 */
.page-about .version-block {
  position: relative;
}

.page-about .timeline-compact {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0;
  padding-left: 2rem;
}

.page-about .tl-track {
  position: absolute;
  left: 0.85rem;
  top: 0;
  bottom: 2rem;
  width: 2px;
  background: linear-gradient(to bottom, var(--about-timeline-color), var(--color-border));
  border-radius: 1px;
}

.page-about .tl-tail {
  position: absolute;
  left: 0.85rem;
  bottom: 0;
  width: 2px;
  height: 1.5rem;
  background: linear-gradient(to bottom, var(--color-border), transparent);
  border-radius: 1px;
}

.page-about .tl-node {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  width: 100%;
  padding-bottom: var(--spacing-md);
}

.page-about .tl-marker {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  position: relative;
}

.page-about .tl-dot {
  position: absolute;
  left: -2rem;
  top: 50%;
  transform: translateY(-50%);
  width: 1.6rem;
  height: 1.6rem;
  background: var(--about-timeline-color);
  border: 3px solid var(--color-bg);
  border-radius: 50%;
  box-shadow: 0 0 0 2px var(--about-timeline-color);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
  z-index: 1;
}

.page-about .tl-node:hover .tl-dot {
  transform: translateY(-50%) scale(1.15);
  box-shadow: 0 0 0 4px var(--about-timeline-color), 0 0 20px rgba(255, 193, 7, 0.25);
}

.page-about .tl-version {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-left: var(--spacing-sm);
  line-height: 1.2;
}

.page-about .tl-node:hover .tl-version {
  color: var(--color-accent);
}

.page-about .tl-body {
  padding: var(--spacing-md) var(--spacing-lg);
  background: var(--about-card-bg);
  border-radius: var(--about-radius);
  border: 1px solid var(--color-border);
  transition: border-color var(--transition-fast), background var(--transition-fast);
  margin-left: 0;
}

.page-about .tl-node:hover .tl-body {
  border-color: var(--about-timeline-color);
  background: var(--about-card-hover);
}

.page-about .tl-changelog {
  list-style: none;
  padding: 0;
  margin: 0 0 var(--spacing-sm);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.page-about .tl-changelog li {
  font-family: var(--font-body);
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  padding-left: var(--spacing-md);
  position: relative;
  line-height: 1.5;
}

.page-about .tl-changelog li::before {
  content: '›';
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: 600;
  font-size: 1.1rem;
}

.page-about .tl-changelog li:hover {
  color: var(--color-text-primary);
}

.page-about .tl-img {
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-sm);
  object-fit: cover;
  background: var(--color-bg);
  margin-top: var(--spacing-xs);
}

.page-about .version-footnote {
  font-family: var(--font-body);
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  margin: var(--spacing-sm) 0 0;
  padding-left: 2rem;
  opacity: 0.75;
}

/* 底部导航链接 */
.page-about .about-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
  justify-content: center;
  padding-top: var(--spacing-xl);
  border-top: 1px solid var(--color-border);
  margin-top: var(--spacing-sm);
}

.page-about .about-links .btn {
  font-family: var(--font-body);
  font-size: 0.95rem;
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius-pill);
  text-decoration: none;
  transition: background var(--transition-fast), color var(--transition-fast), border-color var(--transition-fast);
  font-weight: 500;
}

.page-about .btn-primary {
  background: var(--color-primary);
  color: #fff;
  border: 1px solid var(--color-primary);
}

.page-about .btn-primary:hover {
  background: var(--color-primary-hover);
  border-color: var(--color-primary-hover);
}

.page-about .btn-outline {
  background: transparent;
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
}

.page-about .btn-outline:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  background: rgba(255, 193, 7, 0.06);
}

/* 移动端优先 — 以上为移动端布局 */
/* 桌面端 ≥768px 两列布局 */
@media (min-width: 768px) {
  .page-about {
    padding-left: var(--spacing-xl);
    padding-right: var(--spacing-xl);
    gap: var(--spacing-xl);
  }

  .page-about .about-header {
    padding: var(--spacing-xl) 0 var(--spacing-2xl);
  }

  .page-about .about-brandmark {
    width: 120px;
    height: 120px;
  }

  .page-about .about-layout {
    flex-direction: row;
    align-items: flex-start;
    gap: var(--spacing-2xl);
  }

  .page-about .about-mission {
    width: 32%;
    min-width: 240px;
    max-width: 340px;
    position: sticky;
    top: calc(var(--header-height) + var(--spacing-lg));
    border-left-width: 4px;
    border-radius: 0 var(--about-radius) var(--about-radius) 0;
    padding: var(--spacing-xl) var(--spacing-lg);
  }

  .page-about .about-content {
    flex: 1;
    min-width: 0;
  }

  .page-about .services-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-md);
  }

  .page-about .service-card:last-child {
    grid-column: 1 / -1;
  }

  .page-about .timeline-compact {
    padding-left: 2.5rem;
  }

  .page-about .tl-dot {
    left: -2.5rem;
    width: 1.8rem;
    height: 1.8rem;
  }

  .page-about .tl-track {
    left: 1rem;
  }

  .page-about .tl-tail {
    left: 1rem;
  }

  .page-about .version-footnote {
    padding-left: 2.5rem;
  }

  .page-about .about-links {
    justify-content: flex-start;
    gap: var(--spacing-md);
  }
}

@media (min-width: 1024px) {
  .page-about .services-grid {
    grid-template-columns: 1fr 1fr 1fr;
  }

  .page-about .service-card:last-child {
    grid-column: auto;
  }

  .page-about .about-mission {
    padding: var(--spacing-2xl) var(--spacing-xl);
  }

  .page-about .mission-heading {
    font-size: 1.75rem;
  }
}

/* 确保图片不溢出 */
.page-about img {
  max-width: 100%;
  height: auto;
}

/* 悬停微交互 - 全局卡片氛围 */
.page-about .service-card,
.page-about .tl-body {
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.page-about .service-card:hover,
.page-about .tl-body:hover {
  transform: translateY(-1px);
}

.page-about .service-card[open]:hover {
  transform: none;
}