@media (max-width: 767px) {
#postcard-0 { background-image:url('http://www.goldcore.com/mygoldsaveruk/wp-content/uploads/sites/24/2014/01/mobile_postcard01.jpg'); }

}
			
@media (min-width: 768px) {
#postcard-0 { background-image:url('http://www.goldcore.com/mygoldsaveruk/wp-content/uploads/sites/24/2014/01/postcard01.jpg'); }

}