/* 现代简约风格的CSS样式 */
:root {
  --primary-color: #3498db;
  --secondary-color: #2c3e50;
  --accent-color: #e74c3c;
  --background-color: #f8f9fa;
  --card-background: #ffffff;
  --text-color: #333333;
  --text-light: #666666;
  --border-color: #e1e4e8;
  --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --border-radius: 8px;
  --transition: all 0.3s ease;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background-color: var(--background-color);
  padding: 0;
  margin: 0;
}

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

header {
  background-color: var(--secondary-color);
  color: white;
  padding: 20px 0;
  margin-bottom: 30px;
  box-shadow: var(--shadow);
}

.header-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 0 20px;
}

h1 {
  font-size: 2.5rem;
  margin-bottom: 10px;
  font-weight: 600;
}

.search-container {
  width: 100%;
  max-width: 600px;
  margin: 20px auto;
  position: relative;
}

.search-container input {
  width: 100%;
  padding: 12px 20px;
  font-size: 16px;
  border: 2px solid var(--border-color);
  border-radius: 30px;
  outline: none;
  transition: var(--transition);
}

.search-container input:focus {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.2);
}

.search-container button {
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  background-color: var(--primary-color);
  color: white;
  border: none;
  border-radius: 50%;
  width: 36px;
  height: 36px;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
}

.search-container button:hover {
  background-color: #2980b9;
}

.category-section {
  margin-bottom: 40px;
  background-color: var(--card-background);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  transition: var(--transition);
}

.category-section:hover {
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
  transform: translateY(-2px);
}

.category-header {
  background-color: var(--primary-color);
  color: white;
  padding: 15px 20px;
  font-size: 1.5rem;
  font-weight: 500;
  display: flex;
  align-items: center;
}

.category-header i {
  margin-right: 10px;
  font-size: 1.2em;
}

.category-content {
  padding: 20px;
}

.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 20px;
}

.course-card {
  background-color: var(--card-background);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  padding: 15px;
  transition: var(--transition);
  height: 100%;
  display: flex;
  flex-direction: column;
}

.course-card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-3px);
  border-color: var(--primary-color);
}

.course-card a {
  color: var(--text-color);
  text-decoration: none;
  font-weight: 500;
  display: block;
  transition: var(--transition);
  flex-grow: 1;
}

.course-card a:hover {
  color: var(--primary-color);
}

footer {
  background-color: var(--secondary-color);
  color: white;
  text-align: center;
  padding: 20px;
  margin-top: 40px;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .course-grid {
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  }
  
  h1 {
    font-size: 2rem;
  }
  
  .category-header {
    font-size: 1.3rem;
  }
}

@media (max-width: 480px) {
  .course-grid {
    grid-template-columns: 1fr;
  }
  
  .container {
    padding: 10px;
  }
  
  h1 {
    font-size: 1.8rem;
  }
}

/* 分类颜色 */
.category-programming {
  --category-color: #3498db;
}

.category-programming .category-header {
  background-color: var(--category-color);
}

.category-data-ai {
  --category-color: #9b59b6;
}

.category-data-ai .category-header {
  background-color: var(--category-color);
}

.category-architecture {
  --category-color: #e67e22;
}

.category-architecture .category-header {
  background-color: var(--category-color);
}

.category-devops {
  --category-color: #27ae60;
}

.category-devops .category-header {
  background-color: var(--category-color);
}

.category-product {
  --category-color: #e74c3c;
}

.category-product .category-header {
  background-color: var(--category-color);
}

.category-media {
  --category-color: #f39c12;
}

.category-media .category-header {
  background-color: var(--category-color);
}

.category-lifestyle {
  --category-color: #16a085;
}

.category-lifestyle .category-header {
  background-color: var(--category-color);
}

.category-management {
  --category-color: #8e44ad;
}

.category-management .category-header {
  background-color: var(--category-color);
}

.category-career {
  --category-color: #2c3e50;
}

.category-career .category-header {
  background-color: var(--category-color);
}

.category-technology {
  --category-color: #2980b9;
}

.category-technology .category-header {
  background-color: var(--category-color);
}