كيف تضيف زر الصعود أعلى الصفحة بشكل سلس وجذاب لمدونة بلوجر

#backtop {
  cursor:pointer;
  position:fixed !important;
  position:absolute;
  left:50%;
  bottom:-70px;
  z-index:999;
  background-color:#888;
  -webkit-box-shadow:inset 0 0 25px rgba(0,0,0,0.3),0px 1px 5px #333;
  -moz-box-shadow:inset 0 0 25px rgba(0,0,0,0.3),0px 1px 5px #333;
  box-shadow:inset 0 0 25px rgba(0,0,0,0.3),0px 1px 5px #333;
  width:35px;
  height:50px;
  overflow:hidden;
  text-indent:-999px;
  -webkit-border-top-left-radius:10px;
  -webkit-border-top-right-radius:5px;
  -moz-border-radius-topleft:5px;
  -moz-border-radius-topright:5px;
  border-top-left-radius:5px;
  border-top-right-radius:5px;
}

.feed-links {
  display:none;
}

#backtop::after {
  content:"
  "
  ;
  position:absolute;
  top:7px;
  left:10px;
  width:0;
  height:0;
  border-width:10px 7px;
  border-style:solid;
  border-color:transparent transparent white transparent;
}

    <script src='http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js' type='text/javascript'/>

<div id='backtop'>أعلى الصفحة</div>
<script type='text/javascript'>
//<![CDATA[
$(window).scroll(function(){if($(this).scrollTop()>100){$("#backtop").removeAttr("href");$("#backtop").stop().animate({bottom:"-3",right:"0"}
,{duration:800,queue:false}
)}
else{$("#backtop").stop().animate({bottom:"-50",right:"0"}
,{duration:1000,queue:false}
)}}
);$(function(){$("#backtop").click(function(){$("html,body").animate({scrollTop:0}
,"slow");return false}
)}
);//]]>
</script>