#fundofosco {
    position:fixed;
    _position:absolute;
    top:0px;
    left:0px;
    width :100%;
    height:100%;
    _height:100%;
    background-color:#ffffff;
    z-index:1000;
    filter: alpha(opacity=25);
    opacity: .25;
    display:none;
  }

#flutuante {
    position:fixed;
    _position:absolute;
    top:50px;
	left:17%;
    width :600px;
    height:400px;
    _height:458px;
    background-color:#000000;
    z-index:1001;
    display:none;
    overflow:auto;
    padding:1px;
  }