* {
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            margin: 0;
            padding: 20px;
            background-color: #f5f5f5;
        }
        
        header {
            text-align: center;
            margin-bottom: 30px;
        }
        
        h1 {
            color: #333;
        }
        
        .controls {
            display: flex;
            justify-content: space-between;
            margin-bottom: 20px;
            flex-wrap: wrap;
            gap: 10px;
        }
        
        .sort-options {
            display: flex;
            gap: 10px;
        }
        
        select, button {
            padding: 8px 15px;
            border-radius: 4px;
            border: 1px solid #ddd;
            background-color: white;
            cursor: pointer;
        }
        
        button:hover {
            background-color: #f0f0f0;
        }
        
        .certificate-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
            gap: 20px;
        }
        
        .certificate-card {
            background-color: white;
            border-radius: 8px;
            overflow: hidden;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            transition: transform 0.3s;
            cursor: pointer;
        }
        
        .certificate-card:hover {
            transform: translateY(-5px);
        }
        
        .certificate-img {
            width: fit-content;
            height: 250px;
            object-fit: cover;
            border-bottom: 1px solid #eee;
        }
        
        .certificate-info {
            padding: 15px;
        }
        
        .certificate-info h3 {
            margin-top: 0;
            color: #333;
        }
        
        .certificate-info p {
            margin: 5px 0;
            color: #666;
            font-size: 14px;
        }
        
        .modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: rgba(0, 0, 0, 0.8);
            z-index: 1000;
            justify-content: center;
            align-items: center;
        }
        
        .modal-content {
            background-color: white;
            padding: 20px;
            border-radius: 8px;
            max-width: 90%;
            max-height: 90%;
            overflow: auto;
            position: relative;
        }
        
        .modal-img {
            max-width: 100%;
            max-height: 70vh;
            display: block;
            margin: 0 auto 20px;
        }
        
        .modal-close {
            position: absolute;
            top: 10px;
            right: 10px;
            font-size: 24px;
            cursor: pointer;
            background: none;
            border: none;
        }
        
        .modal-details {
            max-width: 800px;
        }
        
        .modal-actions {
            display: flex;
            justify-content: center;
            gap: 15px;
            margin-top: 20px;
        }
        
        @media (max-width: 768px) {
            .certificate-grid {
                grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
            }
            
            .controls {
                flex-direction: column;
            }
            
            .sort-options {
                justify-content: space-between;
                width: 100%;
            }
        }