.your-world { background-image: url("/media/topbanner.jpg"); } 

@media (min-width: 40em) { .your-world { background-image: url("/media/topbanner.jpg"); } } 
@media (min-width: 64em) { .your-world { background-image: url("/media/topbanner.jpg"); } } 
@media (min-width: 90.063em) { .your-world { background-image: url("/media/topbanner.jpg"); } }