Back To Top 3D Button

/* Back To Top */
#totop{position:fixed; bottom:20px; right:20px; cursor:pointer; display:none; background:url(https://googledrive.com/host/0B-PN1SIugzO-WE5ZeUo5Y3lRVkU) no-repeat center; width:40px; height:40px; box-shadow:0 0 2px 1px #333; border-radius:50%; transition: background 0.2s}
#totop:hover{box-shadow:0 0 2px 1px #000 inset; background: #fff url(https://googledrive.com/host/0B-PN1SIugzO-WE5ZeUo5Y3lRVkU) no-repeat center;}

bottom:20px; button cách phía dưới 20px
right:20px; button cách bên phải 20px

<script src=' https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js ' type='text/javascript'/>

<div id='totop'/>
<script type='text/javascript'>$(function(){$(window).scroll(function(){if($(this).scrollTop()!=0){$(&#39;#totop&#39;).fadeIn();}else{$(&#39;#totop&#39;).fadeOut();}});$(&#39;#totop&#39;).click(function(){$(&#39;body,html&#39;).animate({scrollTop:0},800);});});</script>