#board {
    margin: 0 auto;
    border-spacing: 9px;
    background-color: var(--bs-primary);
    border-collapse: separate;
}

#board td {
    background-color: var(--bs-body-bg);
}

main #board img {
    position: relative;
}

main #board img,
#board td {
    --cell-size: 50px;
    border-radius: var(--cell-size);
    box-sizing: content-box;
    width: var(--cell-size);
    height: var(--cell-size);
}

#board td.PLAYER1 {
    background-color: red;
}

#board td.PLAYER2 {
    background-color: yellow;
}

@media (max-width: 400px) {

    main #board img,
    #board td {
        --cell-size: 32px;
    }
}