pagina=null;
function openPopup (url){
if (pagina != null)
	pagina.close();
	pagina=window.open(url,"","resizable=yes,fullscreen=no,status=no,toolbar=no,scrollbars=yes,menubar=no,width=500,height=400,top=20,left=20");
}
if ((screen.width>800) && (screen.height>600))
{
document.write('<link href="main.css" type="text/css" rel="stylesheet" />');
}
else
{
document.write('<link href="main800.css" type="text/css" rel="stylesheet" />');
}