#cover 
{
    display:none;
    position:absolute;
    left:0px;
    top:0px;
    width:100%;
    height:100%;
    background:gray;
    filter:alpha(Opacity=50);
    opacity:0.5;
    -moz-opacity:0.5;
    -khtml-opacity:0.5;
}
#dialog 
{
    display:none;
    width:780px;
    height:505px;
    position:absolute;
    z-index:100;
    background:white;
    border:1px solid gray;
}