body {
    margin-left: 20%;
    margin-right: 20%;
}

button {
    margin-top: 3em;
}

/*// Small devices (landscape phones, 576px and up)*/
@media (min-width: 576px) {

}

/*// Medium devices (tablets, 768px and up)*/
@media (min-width: 768px) {
    margin-left: 0%;
    margin-right: 0%;
 }

/*// Large devices (desktops, 992px and up)*/
@media (min-width: 992px) {
}

 /*Extra large devices (large desktops, 1200px and up)*/
@media (min-width: 1200px) {
 }