*{
    background-color: black;
    margin:0;padding:0;
}
.cum {
background-color:green;
position: relative;
padding-bottom: 0%; /* play with this number */
 padding-top: 0px; height: 0;}

.cum, iframe,
.cum,
.cum embed{   position: absolute; top: 0; left: 0;  
            width: 100%; height: 100%;           }
}