var tar;
var ua = navigator.userAgent;
var bIE = ua.indexOf("MSIE") != -1;
var bunder7 = false;



if(bIE){
	var pos = ua.indexOf("MSIE");
	var _os = Number(ua.substr(pos+5, 1));
	bunder7 = _os < 7;
}

function setTar(){
	if(ua.indexOf("Win") != -1) document.body.style.fontFamily = "sans-serif";
	if(bunder7){
		tar = document.getElementById("pagetop");
		checkWin();
	}
}

function setTimer(){
	var _timer = setTimeout("checkWin()", 100);
}

function checkWin(){
	var size = getWinsize();
	var scroll = document.documentElement.scrollTop;
	tar.style.top = (size.h - 50) + scroll + "px";
	setTimer();
}

function getWinsize(){
	var _obj = new Object();
	if(window.innerHeight){
		_obj.w = window.innerWidth;
		_obj.h = window.innerHeight;
	}else if (document.all && document.getElementById && (document.compatMode=='CSS1Compat')) {
		_obj.w = window.clientWidth;
		_obj.h = document.documentElement.clientHeight;
	}else if(document.body.clientHeight){
		_obj.w = document.body.clientWidth;
		_obj.h = document.body.clientHeight;
	}else{
		_obj.w = 0;
		_obj.h = 0;
	}
	return _obj;
}




function goTop() {
	var x1 = x2 = x3 = 0;
	var y1 = y2 = y3 = 0;
	if (document.documentElement) {
		x1 = document.documentElement.scrollLeft || 0;
		y1 = document.documentElement.scrollTop || 0;
	}
	if (document.body) {
		x2 = document.body.scrollLeft || 0;
		y2 = document.body.scrollTop || 0;
	}
	x3 = window.scrollX || 0;
	y3 = window.scrollY || 0;
	var x = Math.max(x1, Math.max(x2, x3));
	var y = Math.max(y1, Math.max(y2, y3));
	window.scrollTo(Math.floor(x / 1.4), Math.floor(y / 1.4));
	if (x > 0 || y > 0) {
		window.setTimeout("goTop()", 10);
	}
}