body.chess 
{
    display: block;
    position: absolute;
    background: transparent;
    margin: 0;
    padding: 0;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}
body.chess .boards
{
    display: inline-block;
    width: 400px;
    height: 400px;
    margin: 15px;
}

body.chess .boards.one
{
    width: 50vh;
    height: 50vh;
    margin: 25vh calc(50% - 25vh);
}