/* simple greybox css style
*/
#gbx_overlay {
    width:100%;
    height:100%;
    position:fixed;
    left:0;
    top:0;
    margin:0;
    z-index:2999;
    display:none;
    background:#000; 
    opacity:.50;
    filter: alpha(opacity=50); 
    -moz-opacity: 0.5;
}

* html #gbx_overlay {
    position:absolute; /*IE does not work with position fixed*/
    top:expression((0 + (ignoreMe = document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop)) + 'px'); 
    right: expression((0 + (ignoreMe2 = document.documentElement.scrollLeft ? document.documentElement.scrollLeft : document.body.scrollLeft)) + 'px');
    width:110%;
}



<style>
    #example1 {
        top:50px;
        display:none;
        height:71px;
		background-color:#FFF;
    }
   #example2 {
      top:50px;
      display:none;
      height:701px;
      background:url(testIMG.png);
   }
  </style>