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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f5f7fa;
    color: #333;
}

/* 导航栏 */
.navbar {
    background-color: #2c3e50;
    color: white;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

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

.logo span {
    color: #3498db;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    align-items: center;
    flex-wrap: wrap;
}

.nav-links a {
    color: white;
    text-decoration: none;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: #3498db;
}

/* 容器 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

/* 卡片网格 */
.book-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.book-card {
    background: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    transition: transform 0.3s, box-shadow 0.3s;
}

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

.book-image {
    height: 180px;
    background-color: #ecf0f1;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

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

.book-image-placeholder {
    font-size: 3rem;
    color: #bdc3c7;
}

.book-info {
    padding: 1rem;
}

.book-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #2c3e50;
}

.book-author {
    color: #7f8c8d;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.book-price {
    font-size: 1.3rem;
    font-weight: bold;
    color: #e67e22;
    margin: 0.5rem 0;
}

.book-price del {
    font-size: 0.8rem;
    color: #95a5a6;
    margin-left: 0.5rem;
}

.book-condition {
    display: inline-block;
    padding: 0.2rem 0.5rem;
    background-color: #ecf0f1;
    border-radius: 4px;
    font-size: 0.8rem;
    margin-top: 0.5rem;
}

/* 表单 */
.form-container {
    max-width: 500px;
    margin: 2rem auto;
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 2px 16px rgba(0,0,0,0.1);
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s;
}

.btn-primary {
    background-color: #3498db;
    color: white;
}

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

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

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

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

/* 消息提示 */
.alert {
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1rem;
}

.alert-success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

/* 分页 */
.pagination {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 2rem;
}

.pagination button {
    padding: 0.5rem 1rem;
    border: 1px solid #ddd;
    background: white;
    cursor: pointer;
    border-radius: 4px;
}

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

/* 搜索栏 */
.search-bar {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.search-bar input {
    flex: 1;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
}

.search-bar select {
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 8px;
}

/* 响应式 */
@media (max-width: 768px) {
    .navbar {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        justify-content: center;
    }
    
    .container {
        padding: 1rem;
    }
    
    .book-grid {
        grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    }
}