#board {
    border-collapse: separate;
    margin: 0 auto;
    border: 10px solid;
    border-color: blue yellow blue yellow;
}

#board td {
    border: 3px solid black;
    text-align: center;
    --cell-size: 50px;
    width: var(--cell-size);
    height: var(--cell-size);
}

.PLAYER1 {
    background-color: blue;
}

.PLAYER2 {
    background-color: yellow;
}

.PLAYER1,
.PLAYER2 {
    animation-duration: 1s;
    animation-fill-mode: forwards;
}

@keyframes path {
    to {
        background-color: brown;
        color: white;
    }
}

@media (max-width: 400px) {
    #board td {
        --cell-size: 32px;
    }
}