img {opacity:0;
-moz-transition: opacity 4s; /* Firefox 4 */
-webkit-transition: opacity 4s; /* Safari and Chrome */
-o-transition: opacity 4s;
transition: opacity 4s;
}


.outer {
    display: table;
    position: absolute;
    height: 100%;
    width: 100%;
}

.middle {
    display: table-cell;
    vertical-align: middle;
}

.inner {
    margin-left: auto;
    margin-right: auto; 
    width:100%;
}