#board {
    font-size: 0px;
    border: 3px solid black;
    display: inline-block;
}


.buttons {
    border: 3px solid black;
    width: 150px;
    height: 150px;
}

#green {
    background-color: rgba(0, 195, 60, 0.4);
}

#red {
    background-color: rgba(255, 0, 0, 0.4);
}

#yellow {
    background-color: rgba(237, 237, 0, 0.4);
}

#blue {
    background-color: rgba(0, 0, 255, 0.4);
}