]<style>  
#aposcroll a {  
text-decoration:none;  
color:red;  
}  

#aposcroll:hover {  
background-color:rgba(200, 200, 200, 0.7);  
box-shadow:0px -5px 10px #777;  
}  
</style>  
<div style="padding:30px 5px 0px 5px;position:fixed;top:0px;right:0px;z-index:999;width:70px;height:100%;opacity:0" id="aposcroll"><center><a href="javascript://">▲ Вверх</a></center></div>  

<script>  
// Кнопка Вверх
var as = $('#aposcroll');  
as.click(function() {  
$(document).scrollTo(0, 500);  
});  
document.onscroll = function() {  
var apolst = '0.'+$('body').scrollTop();  
if(apolst.length == 5) {  
as.stop().fadeTo(500, apolst);  
} else if(apolst.length == 4 || apolst.length == 3) {  
as.stop().fadeTo(500, 0);  
};  
   };  </script>