$(function(){
	$(window).scroll(function () {
		var ScrTop = $(document).scrollTop();
		if (ScrTop > 80) {
			$('#pagetop').css({'display':'block','position':'fixed','top':'300px','margin-left':'980px'});
		}
		if (ScrTop < 80) {
			$('#pagetop').css({'display':'none','position':'fixed','top':'300px','margin-left':'980px'});
		}
	});
});