:root {
    --primary: #3498db;
    --primary-dark: #2980b9;
    --secondary: #2ecc71;
    --accent: #e74c3c;
    --light: #f8f9fa;
    --dark: #2c3e50;
    --gray: #7f8c8d;
    --light-gray: #ecf0f1;
    --white: #ffffff;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px 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: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--dark);
    background: var(--light);
    scroll-behavior: smooth;
}

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

.admin-nav {
    background: var(--dark);
    color: var(--white);
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-brand a {
    color: var(--white);
    text-decoration: none;
    font-size: 1.2rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: var(--transition);
}

.nav-brand a:hover {
    color: var(--primary);
}

.nav-links a {
    color: var(--light-gray);
    text-decoration: none;
    margin-left: 20px;
    padding: 8px 12px;
    border-radius: var(--border-radius);
    transition: var(--transition);
    position: relative;
}

.nav-links a:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--primary);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: var(--transition);
    transform: translateX(-50%);
}

.nav-links a:hover::after {
    width: 80%;
}

.admin-main {
    max-width: 1200px;
    margin: 30px auto;
    padding: 0 20px;
}

.admin-footer {
    text-align: center;
    padding: 20px;
    color: #7f8c8d;
    font-size: 0.9rem;
}

.alert {
    padding: 12px 20px;
    margin-bottom: 20px;
    border-radius: 4px;
}

.alert-success { background: #d4edda; color: #155724; }
.alert-error { background: #f8d7da; color: #721c24; }
.alert-info { background: #d1ecf1; color: #0c5460; }

.login-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 70vh;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    padding: 20px;
}

.login-card {
    background: var(--white);
    padding: 40px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 400px;
    animation: fadeInUp 0.6s ease-out;
    position: relative;
    overflow: hidden;
}

.login-card::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 100px;
    height: 100px;
    background: linear-gradient(45deg, rgba(52, 152, 219, 0.1), transparent);
    border-radius: 0 0 0 100%;
}

.login-card h1 {
    text-align: center;
    color: var(--dark);
    margin-bottom: 10px;
    font-size: 1.8rem;
    font-weight: 700;
}

.login-card h2 {
    text-align: center;
    color: var(--gray);
    font-size: 1.2rem;
    margin-bottom: 30px;
    font-weight: 500;
}

.dashboard h1 {
    margin-bottom: 30px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 40px;
}

.stat-card {
    background: var(--white);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    text-align: center;
    transition: var(--transition);
    border-top: 4px solid var(--primary);
    position: relative;
    overflow: hidden;
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 80px;
    height: 80px;
    background: linear-gradient(45deg, rgba(52, 152, 219, 0.1), transparent);
    border-radius: 0 0 0 80px;
}

.stat-card h3 {
    color: var(--gray);
    font-size: 1rem;
    margin-bottom: 10px;
    font-weight: 500;
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    color: var(--dark);
    margin-bottom: 15px;
    position: relative;
    z-index: 1;
}

.stat-card a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    z-index: 1;
}

.stat-card a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.page-header h1 {
    margin: 0;
}

.btn-add {
    background: var(--primary);
    color: var(--white);
    padding: 10px 20px;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
    box-shadow: var(--shadow);
    font-weight: 500;
}

.btn-add:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.data-table {
    width: 100%;
    background: var(--white);
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.data-table th,
.data-table td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid var(--light-gray);
}

.data-table th {
    background: var(--light);
    font-weight: 600;
    color: var(--dark);
    position: sticky;
    top: 0;
    z-index: 100;
}

.data-table tr {
    transition: var(--transition);
}

.data-table tr:hover {
    background: rgba(52, 152, 219, 0.05);
}

.data-table tr:last-child td {
    border-bottom: none;
}

.data-table a {
    color: var(--primary);
    text-decoration: none;
    margin-right: 10px;
    transition: var(--transition);
    padding: 5px 10px;
    border-radius: var(--border-radius);
}

.data-table a:hover {
    background: rgba(52, 152, 219, 0.1);
    color: var(--primary-dark);
}

.btn-delete {
    background: var(--accent);
    color: var(--white);
    border: none;
    padding: 5px 10px;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.9rem;
    transition: var(--transition);
}

.btn-delete:hover {
    background: #c0392b;
    transform: translateY(-1px);
}

.badge {
    display: inline-block;
    padding: 4px 10px;
    border-radius: 12px;
    font-size: 0.85rem;
}

.badge-success { background: #d4edda; color: #155724; }
.badge-draft { background: #fff3cd; color: #856404; }

.form-container {
    background: var(--white);
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    max-width: 800px;
    animation: fadeInUp 0.6s ease-out;
}

.form-container h1 {
    margin-bottom: 30px;
    color: var(--dark);
    font-size: 1.8rem;
    font-weight: 700;
}

.form-section {
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 1px solid var(--light-gray);
}

.form-section:last-of-type {
    border-bottom: none;
}

.form-section h3 {
    margin-bottom: 15px;
    color: var(--dark);
    font-size: 1.2rem;
    font-weight: 600;
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    color: var(--gray);
    font-weight: 500;
}

.form-group input[type="text"],
.form-group input[type="number"],
.form-group input[type="password"],
.form-group input[type="email"],
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--light-gray);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
    background: var(--white);
}

.form-group input[type="text"]:focus,
.form-group input[type="number"]:focus,
.form-group input[type="password"]:focus,
.form-group input[type="email"]:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

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

.form-group small {
    display: block;
    margin-top: 5px;
    color: var(--gray);
    font-size: 0.85rem;
}

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 15px;
}

.form-actions {
    display: flex;
    gap: 10px;
    margin-top: 30px;
    padding-top: 20px;
    border-top: 1px solid var(--light-gray);
}

.btn-submit {
    background: var(--primary);
    color: var(--white);
    border: none;
    padding: 12px 30px;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.btn-submit:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-cancel {
    background: var(--gray);
    color: var(--white);
    padding: 12px 30px;
    text-decoration: none;
    border-radius: var(--border-radius);
    font-weight: 500;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.btn-cancel:hover {
    background: #6c757d;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.status-rented { background: #fff3cd; color: #856404; }
.status-unavailable { background: #e2e3e5; color: #383d41; }

/* 动画效果 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 响应式设计 */
@media (max-width: 768px) {
    .admin-nav {
        flex-direction: column;
        height: auto;
        padding: 15px 20px;
        gap: 10px;
    }
    
    .nav-links {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
        gap: 10px;
    }
    
    .nav-links a {
        margin-left: 0;
    }
    
    .admin-main {
        margin: 20px auto;
        padding: 0 15px;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .form-actions {
        flex-direction: column;
    }
    
    .btn-submit,
    .btn-cancel {
        width: 100%;
        text-align: center;
    }
    
    .login-card {
        padding: 30px;
    }
}

@media (max-width: 480px) {
    .login-card {
        padding: 20px;
    }
    
    .stat-card {
        padding: 20px;
    }
    
    .form-container {
        padding: 20px;
    }
    
    .data-table th,
    .data-table td {
        padding: 10px;
        font-size: 0.9rem;
    }
}