html { height: 100% }
  body { height: 100%; margin: 10px; padding: 0px }
  #map_canvas { height: 100% }
   .hiddenDiv {
    visibility:hidden;
    }

<style type="text/css">
            .modal-overlay  
    {  
        position:fixed;  
        top:0;  
        right:0;  
        bottom:0;  
        left:0;  
        height:100%;  
        width:100%;  
        margin:0;  
        padding:0;  
        background:#fff;  
        opacity:0.90;  
        filter: alpha(opacity=90);  
        -moz-opacity: 0.90;  
        z-index:101;  
    }  
    .modal-window  
    {  
        position:fixed;  
        top:50%;  
        left:50%;  
        margin:0;  
        padding:0;  
        z-index:102;  
    }  
    .close-window  
    {  
        position:absolute;  
        width:32px;  
        height:32px;  
        right:8px;  
        top:8px;  
        background:transparent url('http://www.google.com/intl/en_us/mapfiles/close.gif') no-repeat scroll right top;  
        text-indent:-99999px;  
        overflow:hidden;  
        cursor:pointer;  
        opacity:.5;  
        filter: alpha(opacity=50);  
        -moz-opacity: 0.5;  
    }  
    .close-window:hover  
    {  
        opacity:.99;  
        filter: alpha(opacity=99);  
        -moz-opacity: 0.99;  
    }  
    </style>