Page small function-back to top

<div id= "To_top" >
<div class= "dp_float" ><a><br/> Back Top </a></div>
</div>

<%--returns to the top: Baoxw--%>
<style>
body{margin:0; padding:0}
#to_top {padding-bottom:0px; margin:0px; font:14px/20px Arial; Background: #06c; Position:absolute; Cursor:pointer; Color: #fff}
</style>
<script>
window.onload = function () {
var oTop = document.getElementById ("To_top");
var screenw = Document.documentElement.clientWidth | | document.body.clientWidth;
var screenh = Document.documentElement.clientHeight | | document.body.clientHeight;
OTop.style.left = screenw-otop.offsetwidth + "px";
OTop.style.top = screenh-otop.offsetheight + "px";
Window.onscroll = function () {
var scrolltop = Document.documentElement.scrollTop | | document.body.scrollTop;
OTop.style.top = screenh-otop.offsetheight + scrolltop + "px";
}
Otop.onclick = function () {
Document.documentElement.scrollTop = Document.body.scrollTop =0;
}
}
</script>
<%--return top: Baoxw--%>

Page Small function-back to top