window.onscroll=function(){scrollFunction()};function scrollFunction(){if(document.body.scrollTop>20||document.documentElement. scrollTop>20){document.getElementById("go_top").style.display="block"}else{document.getElementById("go_top").style.display="none"} }
document.getElementById("go_top").onclick=function(){document.body.scrollTop=0;document.documentElement.scrollTop=0}