function getPageSizes(type){    
    var viewportwidth;
    var viewportheight;
    
    // the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight
    
    if (typeof window.innerWidth != 'undefined') {
      viewportwidth = window.innerWidth;
      viewportheight = window.innerHeight;
    }
    
    // IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)
    
    else if (typeof document.documentElement != 'undefined' && typeof document.documentElement.clientWidth != 'undefined' && document.documentElement.clientWidth != 0) {
       viewportwidth = document.documentElement.clientWidth;
       viewportheight = document.documentElement.clientHeight;
    }
    
    // older versions of IE
    
    else
    {
       viewportwidth = document.getElementsByTagName('body')[0].clientWidth;
       viewportheight = document.getElementsByTagName('body')[0].clientHeight;
    }
    
    // A la altura total se le resta 180px (100 de la cabecera y 80 del pie de página
    //document.getElementById("mainSpace").style.height=(viewportheight-145) + "px";
    
    // return page size
    if(type == 'width')
    	return viewportwidth;
    else
    if(type == 'height')
    	return viewportheight;
    	
    
}