body {
            background-color: #007bff;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            margin: 0;
        }
        .container {
            max-width: 800px;
            background-color: white;
            border-radius: 10px;
            padding: 30px;
            box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
            text-align: center;
        }
        h1 {
            font-weight: bold;
            font-style: italic;
            text-shadow: 2px 2px 5px rgba(0, 0, 0, 0.3);
            margin-bottom: 20px;
        }
        .btn {
            padding: 10px 20px;
            font-size: 16px;
            margin: 5px;
            border-radius: 5px;
            display: inline-flex;
            align-items: center;
            justify-content: center;
        }
        .btn i {
            margin-right: 8px;
        }
        .btn-success {
            background-color: #28a745;
            color: white;
        }
        .btn-danger {
            background-color: #dc3545;
            color: white;
        }
        .btn-warning {
            background-color: #ffc107;
            color: white;
        }
        .btn-primary {
            background-color: #007bff;
            color: white;
        }
        .correct {
            color: green;
        }
        .incorrect {
            color: red;
        }
        .difficulty {
            margin-bottom: 20px;
        }