form { border: 10px solid #FFFFFF }

table {
    height: 400px;
    width: 100%;
}
@media screen and (max-width: 500px) {
    table tr td:nth-child(3) {
        clear: both;
        display: block;
        width: 100%;
    }
    table tr td:nth-child(1), table tr td:nth-child(2) {
        display: block;
        width: 100%;
    }
}