@media only screen and (max-width: 480px) {
    #mo {width:400px;height:300px;}
}
@media only screen and (min-width: 480px) and (max-width: 768px) {
    #mo {width:400px;height:300px;}
}
@media only screen and (min-width: 768px) and (max-width: 959px) {
    #mo {width:100%;height:100%;}
}
@media only screen and (min-width: 959px) {
    #mo {width:100%;height:100%;}
}