#crossfade {
    position :relative;
    /* height:250px;
    width:400px; */
}

#crossfade img {
    position:absolute;
    right:0;
    opacity: 1;
    -webkit-transition: opacity 2s ease-in-out;
    -moz-transition: opacity 2s ease-in-out;
    -o-transition: opacity 2s ease-in-out;
    -ms-transition: opacity 2s ease-in-out;    
    transition: opacity 2s ease-in-out;
}
    
#crossfade img.top:hover {
    opacity:0;
}

@media screen and (max-width: 500px) {
    #crossfade {
        position:static;
        width: 70%;
    }

    #crossfade img {
        position: absolute;
        width: inherit;
        left: 15%;
    }
}