#crossfade {
    /*something something :D*/
   
}
#crossfade img {
    position:absolute;
    left:0;
    opacity: 1;
    -webkit-transition: opacity 1s ease-in-out;
    -moz-transition: opacity 1s ease-in-out;
    -o-transition: opacity 1s ease-in-out;
    -ms-transition: opacity 1s ease-in-out;    
    transition: opacity 1s ease-in-out;
}
 
#crossfade img.top:hover {
    opacity:0;
}