table{
    border-collapse: collapse;
    margin: 20px auto;
}

td {
    width: 50px;
    height: 50px;
    border: 1px solid #000;
    text-align: center;
    font-size: 30px;
}

tr:nth-child(odd) td:nth-child(odd),
tr:nth-child(even) td:nth-child(even) {
    background-color: #D3D3D3;
}

tr:nth-child(odd) td:nth-child(even),
tr:nth-child(even) td:nth-child(odd) {
    background-color: #fff;
}