#overlay{
        position: absolute;
        top: 0;
        left: 0;
        z-index: 90;
        width: 100%;
        height: 500px;
        background-color: #000;
        filter:alpha(opacity=50);
        -moz-opacity: 0.5;
        opacity: 0.5;
        }
#loading{
        position: absolute;
        top: 60%;
        left: 0%;
        height: 25%;
        width: 100%;
        text-align: center;
        line-height: 0;
        }

#imagenesEj1 img{
width:80px;
height:60px;
}