#toTop {
    display: none;
    position: fixed;
    bottom: 200px;
    right: 100px;
    width: 70px;
    height: 70px;
   background:url(imagesup.jpg) no-repeat;
    opacity: 0.4;
    filter: alpha(opacity=40); /* For IE8 and earlier */
}
#toTop:hover {
    opacity: 0.8;
    filter: alpha(opacity=80); /* For IE8 and earlier */
}