div.dimmer
{
    visibility:hidden;
    position:fixed;
    left:0px;
    top:0px;
    padding:40px;
    background-image:url(dimmer.png);
    /* ieWin only stuff */
        /* with this trick only IE
           manage the following 2 attributes */
    _background-image:none;
    _filter:progid:DXImageTransform.Microsoft.AlphaImageLoader
        (enabled=true, sizingMethod=scale src='dimmer.png');
}