/* 全局变量 */
:root {
  --color-primary: #3b82f6;
  --color-primary-light: #60a5fa;
  --color-secondary: #e0f2fe;
  --color-gray-50: #f9fafb;
  --color-gray-100: #f3f4f6;
  --color-gray-200: #e5e7eb;
  --color-gray-800: #1f2937;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --transition-base: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 字体设置 */
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* 平滑滚动 */
html {
  scroll-behavior: smooth;
}

/* 导航栏透明效果 */
.nav-scrolled {
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow-sm);
  transition: var(--transition-base);
}

/* 导航菜单悬停下划线 */
.nav-link {
  position: relative;
  transition: var(--transition-base);
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-primary);
  transition: width 0.3s ease;
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* 卡片悬停效果 */
.card-hover {
  transition: var(--transition-base);
}

.card-hover:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
}

/* 按钮悬停效果 */
.btn-primary {
  transition: var(--transition-base);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* Hero区背景渐变 */
.hero-gradient {
  background: linear-gradient(135deg, #e0f2fe 0%, #ffffff 50%, #f0f9ff 100%);
}

/* 图片加载占位 */
.img-placeholder {
  background: linear-gradient(90deg, var(--color-gray-100) 0%, var(--color-gray-200) 50%, var(--color-gray-100) 100%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
}

@keyframes shimmer {
  0% {
    background-position: -200% 0;
  }
  100% {
    background-position: 200% 0;
  }
}

/* 时间线样式 */
.timeline-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 8px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--color-primary);
  box-shadow: 0 0 0 4px var(--color-secondary);
}

.timeline-item::after {
  content: '';
  position: absolute;
  left: 5px;
  top: 20px;
  width: 2px;
  height: calc(100% - 12px);
  background: var(--color-gray-200);
}

.timeline-item:last-child::after {
  display: none;
}

/* 表单样式增强 */
.form-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-secondary);
}

/* 响应式调整 */
@media (max-width: 768px) {
  .card-hover:hover {
    transform: translateY(-4px);
  }
  
  .timeline-item::before {
    left: -20px;
  }
  
  .timeline-item::after {
    left: -15px;
  }
}

/* 页面淡入动画 */
.fade-in {
  animation: fadeIn 0.6s ease-in;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* 隐藏滚动条但保持滚动功能 */
.hide-scrollbar::-webkit-scrollbar {
  display: none;
}

.hide-scrollbar {
  -ms-overflow-style: none;
  scrollbar-width: none;
}