body {
            font-family: Arial, sans-serif;
        }
        form {
            max-width: 300px;
            margin: 0 auto;
            padding: 20px;
            background-color: #f4f4f4;
            border: 1px solid #ccc;
            border-radius: 5px;
        }
        h1 {
            text-align: center;
        }
        .number-input {
            width: 100%;
            padding: 10px;
            margin: 10px -10px;
            border: 1px solid #ccc;
            border-radius: 5px;
        }
        .submit-btn {
            background-color: #007BFF;
            color: white;
            padding: 10px 20px;
            border: none;
            border-radius: 5px;
            cursor: pointer;
        }
        .submit-btn:hover {
            background-color: #0056b3;
        }