function FB_ltpx(){
	 var windowWidth = document.documentElement.clientWidth;
	 var windowHeight = document.documentElement.clientHeight;
	 if(windowWidth>1980){
			document.body.style.backgroundPositionX="center";
		}
		if(windowHeight>888){
			document.body.style.backgroundPositionY="center";
		}	 
	 var popupHeight = parseInt(document.getElementById("cay").offsetHeight);
	 var box_top=(windowHeight-popupHeight)/2;
	 if(popupHeight>windowHeight){box_top=0}
	 document.getElementById("cay").style.marginTop=box_top+"px";
}
window.onload=function(){
window.onresize = FB_ltpx;
FB_ltpx();
}