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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background-color: #f5f7fa;
  color: #333;
  line-height: 1.6;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* 导航栏 */
.navbar {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

.navbar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: bold;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-menu a {
  color: rgba(255, 255, 255, 0.8);
  text-decoration: none;
  font-weight: 500;
  transition: color 0.3s;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: white;
}

/* 按钮样式 */
.btn-primary {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  padding: 10px 24px;
  border-radius: 25px;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 500;
  text-decoration: none;
  display: inline-block;
  transition: transform 0.2s, box-shadow 0.2s;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
  background: white;
  color: #667eea;
  border: 2px solid #667eea;
  padding: 8px 20px;
  border-radius: 25px;
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 500;
  text-decoration: none;
  display: inline-block;
  transition: all 0.2s;
}

.btn-secondary:hover {
  background: #667eea;
  color: white;
}

/* 卡片样式 */
.card {
  background: white;
  border-radius: 16px;
  padding: 20px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
  transition: transform 0.2s, box-shadow 0.2s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
}

/* 章节标题 */
.section-title {
  font-size: 1.5rem;
  font-weight: 600;
  color: #2c3e50;
  margin: 30px 0 20px;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* 文本居中 */
.text-center {
  text-align: center;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .nav-menu {
    gap: 1rem;
    font-size: 0.9rem;
  }

  .section-title {
    font-size: 1.3rem;
  }
}