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

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  line-height: 1.6;
  color: #333;
  background-color: #f5f5f5;
}

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

/* 头部样式 */
header {
  background-color: #2c3e50;
  color: white;
  padding: 15px 0;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

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

.logo {
  font-size: 1.5rem;
  font-weight: bold;
  text-decoration: none;
  color: white;
}

.nav {
  display: flex;
  gap: 20px;
}

.nav a {
  color: white;
  text-decoration: none;
  padding: 5px 10px;
  border-radius: 4px;
  transition: background-color 0.3s;
}

.nav a:hover {
  background-color: #34495e;
}

/* 主内容样式 */
main {
  padding: 40px 0;
  min-height: calc(100vh - 140px);
}

/* 卡片样式 */
.card {
  background-color: white;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  padding: 20px;
  margin-bottom: 20px;
  transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 5px 20px rgba(0,0,0,0.15);
}

/* 分类卡片 */
.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.category-card {
  text-decoration: none;
  color: inherit;
}

.category-card h3 {
  color: #2c3e50;
  margin-bottom: 10px;
}

.category-card p {
  color: #666;
}

/* 资源列表 */
.resource-list {
  display: flex;
  flex-direction: column;
  gap: 15px;
}

.resource-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px;
  background-color: white;
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.resource-info {
  flex: 1;
}

.resource-info h3 {
  margin-bottom: 5px;
  color: #2c3e50;
}

.resource-meta {
  display: flex;
  gap: 20px;
  font-size: 0.9rem;
  color: #666;
}

.download-btn {
  background-color: #3498db;
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 4px;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.3s;
}

.download-btn:hover {
  background-color: #2980b9;
}

/* 表单样式 */
.form-container {
  max-width: 500px;
  margin: 0 auto;
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  margin-bottom: 8px;
  font-weight: 500;
  color: #333;
}

.form-group input,
.form-group textarea,
.form-group select {
  width: 100%;
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 4px;
  font-size: 1rem;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
  outline: none;
  border-color: #3498db;
  box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
}

.btn {
  display: inline-block;
  background-color: #3498db;
  color: white;
  border: none;
  padding: 10px 20px;
  border-radius: 4px;
  cursor: pointer;
  font-size: 1rem;
  text-decoration: none;
  transition: background-color 0.3s;
}

.btn:hover {
  background-color: #2980b9;
}

.btn-primary {
  background-color: #27ae60;
}

.btn-primary:hover {
  background-color: #229954;
}

.btn-danger {
  background-color: #e74c3c;
}

.btn-danger:hover {
  background-color: #c0392b;
}

.btn-secondary {
  background-color: #95a5a6;
}

.btn-secondary:hover {
  background-color: #7f8c8d;
}

/* 错误和成功消息 */
.message {
  padding: 15px;
  margin-bottom: 20px;
  border-radius: 4px;
}

.message-error {
  background-color: #ffeaea;
  color: #e74c3c;
  border: 1px solid #fadbd8;
}

.message-success {
  background-color: #eafaf1;
  color: #27ae60;
  border: 1px solid #d5f5e3;
}

/* 管理员面板样式 */
.admin-sidebar {
  width: 250px;
  height: 100vh;
  background-color: #2c3e50;
  color: white;
  position: fixed;
  top: 0;
  left: 0;
  padding-top: 60px;
}

.admin-content {
  margin-left: 250px;
  padding: 20px;
}

.admin-nav {
  list-style: none;
}

.admin-nav li {
  margin-bottom: 10px;
}

.admin-nav a {
  color: white;
  text-decoration: none;
  display: block;
  padding: 15px 20px;
  transition: background-color 0.3s;
}

.admin-nav a:hover {
  background-color: #34495e;
}

.admin-nav .active {
  background-color: #3498db;
}

/* 表格样式 */
.table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 20px;
}

.table th,
.table td {
  padding: 12px;
  text-align: left;
  border-bottom: 1px solid #ddd;
}

.table th {
  background-color: #f8f9fa;
  font-weight: 600;
}

.table tr:hover {
  background-color: #f5f5f5;
}

/* 仪表盘样式 */
.dashboard-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
  margin-bottom: 30px;
}

.stats-card {
  background-color: white;
  padding: 25px;
  border-radius: 8px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  text-align: center;
}

.stats-card h3 {
  color: #666;
  font-size: 1.1rem;
  margin-bottom: 15px;
}

.stats-number {
  font-size: 2.5rem;
  font-weight: bold;
  color: #3498db;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    gap: 15px;
  }
  
  .resource-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 15px;
  }
  
  .categories-grid {
    grid-template-columns: 1fr;
  }
  
  .admin-sidebar {
    width: 100%;
    height: auto;
    position: relative;
  }
  
  .admin-content {
    margin-left: 0;
  }
}

/* 登录页面样式 */
.login-container {
  max-width: 400px;
  margin: 100px auto;
}

.login-container h2 {
  text-align: center;
  margin-bottom: 30px;
  color: #2c3e50;
}

/* 页脚样式 */
footer {
  background-color: #2c3e50;
  color: white;
  text-align: center;
  padding: 20px 0;
  margin-top: 40px;
}

/* 分页样式 */
.pagination {
  display: flex;
  justify-content: center;
  margin-top: 30px;
  gap: 10px;
}

.pagination a {
  padding: 8px 16px;
  background-color: white;
  border: 1px solid #ddd;
  border-radius: 4px;
  text-decoration: none;
  color: #3498db;
  transition: all 0.3s;
}

.pagination a:hover {
  background-color: #3498db;
  color: white;
  border-color: #3498db;
}

.pagination .active {
  background-color: #3498db;
  color: white;
  border-color: #3498db;
}

/* 404页面 */
.not-found {
  text-align: center;
  padding: 60px 0;
}

.not-found h1 {
  font-size: 3rem;
  color: #e74c3c;
  margin-bottom: 20px;
}

.not-found p {
  font-size: 1.2rem;
  color: #666;
  margin-bottom: 30px;
}