body {
background-color: bisque;
}

table {
    margin-top: 20vmin;
    background-color: gray;
    margin-left: auto;
    margin-right: auto;
    border: 1px solid gray;
    empty-cells: hide;
    text-align: center;
    width: 400px;
    height: 400px;
}

th, tr{
    border: 5px solid gray;
    background-color:   bisque;
}

a {
    position: absolute;
    top: 1vh;
    left: 2vw;
    font-size: 3vmin;
    color: black;
}

footer {
    position: absolute;
    bottom: 1vh;
    left: 50vw;
    transform: translateX(-50%);
    font-size: 2vmin;
}