@media screen and (min-width: 768px){
    body{
        background-color: red;
    }
}
@media screen and (min-width: 992px)
{
    body{
        background-color: grey;
    }
}
@media screen and (min-width: 1200px)
{
    body{
        background-color: palevioletred;
    }
}