var getdiv=document.getelementbyid('returntop');
getdiv.onclick=function(){
	window.scrollto(0,0);
}
window.onscroll=function(){
	if(document.documentelement.scrolltop){
		getdiv.style.display="block";
	}else if(document.body.scrolltop){
		getdiv.style.display="block";
	}else{
		getdiv.style.display="block";	
	}
}
function getwinsize(){
	var winheight=window.innerheight,winwidth=window.innerwidth;
	if(document.documentelement.clientheight){
		winheight=document.documentelement.clientheight;
		winwidth=document.documentelement.clientwidth;
	}else{
		winheight=document.body.clientheight;
		winwidth=document.body.clientwidth;
	}
    var height=winheight-50;
	var width=winwidth-100;
	getdiv.style.top=height+"px";
	getdiv.style.left=width+"px";
}
getwinsize();
window.onresize=getwinsize;