//绝对居中
var btop=window.screenTop;
var bheight=window.screen.availHeight;
if(navigator.userAgent.indexOf("Firefox")>0){
	if(bheight-105-23>620){
		//document.getElementById("indexallwrap").style.marginTop=(parseInt(bheight)-105-23-620)/2+"px";
		document.getElementById("main").style.marginTop="20px";
	}
}
else{
	if(bheight-btop-23>620){
		document.getElementById("main").style.marginTop=(parseInt(bheight)-parseInt(btop)-23-620)/2+"px";		
	}
}