style.css

* {
    margin: 0;
    padding: 0;
}

form {
    font-family: sans-serif;
    font-size: 14px;
    display: flex;
    flex-direction: row;
    justify-content: center;
    margin: auto;
    box-shadow: 0 0 10px #bbb;
}

label, input, select {
    padding: .5rem;
    margin: 1rem .5rem;
}

input, select {
    border-radius: 3px;
    border: solid 2px #d1d1d1;
    box-shadow: 0 0 10px #ddd;
    background-color: #e5e5e5;
    cursor: pointer;
}

.p4 table {
    position: relative;
    margin: auto;
    transform: translateY(50%);
    border: 2px blue solid;
    background-color: blue;
    box-shadow: 0 0 10px #aaa;
}

.p4 td {
    width: 4rem;
    height: 4rem;
    border: 2px blue solid;
    border-radius: 50%;
    box-shadow: 0 0 10px #aaa inset;
    background-color: white;
    cursor: pointer;
}

.p4 td.player1 {
    background-color: red;
}

.p4 td.player2 {
    background-color: yellow;
}