/* 设计令牌 */
:root {
  --color-primary: #333333;
  --color-secondary: #e8e8e8;
  --color-background: #fefefe;
  --color-accent: #999999;
  --font-family-sans: 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 3rem;
  --spacing-xl: 4rem;
  --border-radius-sm: 4px;
  --border-radius-md: 8px;
  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-md: 0 4px 8px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 16px rgba(0, 0, 0, 0.1);
}

/* 全局样式 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family-sans);
  color: var(--color-primary);
  background-color: var(--color-background);
  line-height: 1.6;
}

/* 导航栏样式 */
.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(254, 254, 254, 0.9);
  backdrop-filter: blur(10px);
  z-index: 1000;
  padding: var(--spacing-sm) 0;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-sm);
  display: flex;
  justify-content: center;
  align-items: center;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--spacing-md);
}

.nav-link {
  color: var(--color-primary);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s ease;
}

.nav-link:hover {
  color: var(--color-accent);
}

/* 轮播图样式 */
.carousel-container {
  position: relative;
  width: 100%;
  height: 100vh;
  overflow: hidden;
}

.carousel-slide {
  position: absolute;
  width: 100%;
  height: 100%;
  opacity: 0;
  transition: opacity 1s ease;
}

.carousel-slide.active {
  opacity: 1;
}

.carousel-image {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.carousel-text {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  color: white;
  font-size: 2.5rem;
  font-weight: 300;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
}

.carousel-indicators {
  position: absolute;
  bottom: var(--spacing-lg);
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: var(--spacing-xs);
}

.indicator {
  width: 40px;
  height: 3px;
  background: rgba(255, 255, 255, 0.5);
  cursor: pointer;
  transition: background 0.3s ease;
}

.indicator.active {
  background: white;
}

/* 按钮样式 */
.btn {
  display: inline-block;
  padding: var(--spacing-sm) var(--spacing-md);
  background: transparent;
  border: 1px solid var(--color-primary);
  color: var(--color-primary);
  text-decoration: none;
  transition: all 0.3s ease;
  margin: var(--spacing-sm) 0;
}

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

/* 网格布局样式 */
.grid-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-md) var(--spacing-sm);
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-md);
  margin-top: var(--spacing-md);
}

.grid-item {
  overflow: hidden;
  border-radius: var(--border-radius-md);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.grid-item:hover {
  transform: scale(1.02);
  box-shadow: var(--shadow-lg);
}

.grid-image {
  width: 100%;
  height: 400px;
  object-fit: cover;
}

.grid-title {
  padding: var(--spacing-sm);
  background: var(--color-background);
  text-align: center;
}

/* 筛选标签样式 */
.filter-container {
  display: flex;
  justify-content: center;
  gap: var(--spacing-sm);
  margin: var(--spacing-md) 0;
  flex-wrap: wrap;
}

.filter-tag {
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--color-secondary);
  border: none;
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  transition: all 0.3s ease;
}

.filter-tag:hover,
.filter-tag.active {
  background: var(--color-primary);
  color: var(--color-background);
}

/* 图文交错布局 */
.alternating-section {
  display: flex;
  align-items: center;
  margin: var(--spacing-xl) 0;
}

.alternating-image {
  flex: 1;
  width: 100%;
  height: 500px;
  object-fit: cover;
}

.alternating-text {
  flex: 1;
  padding: var(--spacing-lg);
  background: var(--color-background);
}

.alternating-section:nth-child(even) {
  flex-direction: row-reverse;
}

/* 时间线布局 */
.timeline {
  max-width: 800px;
  margin: var(--spacing-xl) auto;
  position: relative;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 50%;
  top: 0;
  bottom: 0;
  width: 1px;
  background: var(--color-secondary);
}

.timeline-item {
  display: flex;
  justify-content: flex-end;
  padding-right: var(--spacing-md);
  position: relative;
  margin: var(--spacing-lg) 0;
  width: 50%;
}

.timeline-item:nth-child(even) {
  align-self: flex-end;
  justify-content: flex-start;
  padding-left: var(--spacing-md);
  padding-right: 0;
  left: 50%;
}

.timeline-content {
  background: var(--color-background);
  padding: var(--spacing-md);
  border-radius: var(--border-radius-md);
  box-shadow: var(--shadow-sm);
}

.timeline-dot {
  position: absolute;
  width: 12px;
  height: 12px;
  background: var(--color-primary);
  border-radius: 50%;
  top: 50%;
  transform: translateY(-50%);
  right: -6px;
}

.timeline-item:nth-child(even) .timeline-dot {
  left: -6px;
  right: auto;
}

/* 页脚样式 */
.footer {
  text-align: center;
  padding: var(--spacing-md) 0;
  color: var(--color-accent);
  font-size: 0.9rem;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .nav-menu {
    gap: var(--spacing-sm);
  }
  
  .carousel-text {
    font-size: 1.8rem;
  }
  
  .alternating-section,
  .alternating-section:nth-child(even) {
    flex-direction: column;
  }
  
  .timeline::before {
    left: 20px;
  }
  
  .timeline-item,
  .timeline-item:nth-child(even) {
    width: 100%;
    padding-left: 50px;
    padding-right: var(--spacing-sm);
    left: 0;
  }
  
  .timeline-dot {
    left: 14px;
    right: auto;
  }
  
  .timeline-item:nth-child(even) .timeline-dot {
    left: 14px;
  }
}

@media (max-width: 480px) {
  .carousel-text {
    font-size: 1.5rem;
  }
  
  .grid {
    grid-template-columns: 1fr;
  }
  
  .filter-container {
    padding: 0 var(--spacing-sm);
  }
}