.header-mobile { display:none; }
.header-desktop img,.header-mobile img { width:100%;}

@media (orientation: portrait) {
    .header-mobile { display:block; }
    .header-desktop { display:none; }

}
@media screen and ( max-width:500px){
    .header-mobile { display:block; }
    .header-desktop { display:none; }
    }