table {
        border-collapse: collapse;
        width: 300px;
    }

    td, th {
        border: none;
        padding: 10px;
        text-align: center;
        width: 10px;
    }



    tr:nth-child(4) td {
        border-top: 1px solid black;
    }

    tr:last-child td {
        border-bottom: 1px solid black;
    }

    button {
        margin-top: 10px;
    }

    #result {
        margin-top: 10px;
        font-size: 18px;
    }
	
	.input-field{
		width: 20px;
		font-size: 32px
	}