table {
    width:70%;
    font-size: large;
}
td {
    width:20%;
    position:relative;
}
td:after{
    content:'';
    display:block;
    margin-top:100%;
}
td .square {
    position:absolute;
    top:0;
    bottom:0;
    left:0;
    right:0;
    background: white;
    border-style: solid;
}

td .free {
    position:absolute;
    top:0;
    bottom:0;
    left:0;
    right:0;
    background: gold;
}

.free:active{
    background-color: green;
}

.clearButton {
    color: white;
    background-color: red;
    height: 45px;
}