js 实现右下角提示框

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<style type="text/css">
* {margin:0px;padding:0px;}
html,body { height:100%;}
body { font-size:14px; line-height:24px;}
#tip {
position: absolute;
right: 0px;
bottom: 0px;
height: 0px;
width: 180px;
border: 1px solid #CCCCCC;
background-color: #eeeeee;
padding: 1px;
overflow:hidden;
display:none;
font-size:12px;
z-index:10;
}
#tip p { padding:6px;}
#tip h1,#detail h1 {
font-size:14px;
height:25px;
line-height:25px;
background-color:#0066CC;
color:#FFFFFF;
padding:0px 3px 0px 3px;
filter: Alpha(Opacity=100);
}
#tip h1 a,#detail h1 a {
float:right;
text-decoration:none;
color:#FFFFFF;
}
#shadow {
position:absolute;
width:100%;
height:100%;
background-color:#000000;
z-index:11;
filter: Alpha(Opacity=70);
display:none;
overflow:hidden;
}
#detail {
width:500px;
height:200px;
border:3px double #ccc;
background-color:#FFFFFF;
position:absolute;
z-index:30;
display:none;
left:30%;
top:30%
}
</style>
<script type="text/javascript">
var handle;
function start()
{
var obj = document.getElementById("tip");
if (parseInt(obj.style.height)==0)
{ obj.style.display="block";
handle = setInterval("changeH('up')",2);
}else
{
     handle = setInterval("changeH('down')",2)
}
}
function changeH(str)
{
var obj = document.getElementById("tip");
if(str=="up")
{
if (parseInt(obj.style.height)>200)
   clearInterval(handle);
else
   obj.style.height=(parseInt(obj.style.height)+8).toString()+"px";
}
if(str=="down")
{
if (parseInt(obj.style.height)<8)
{ clearInterval(handle);
   obj.style.display="none";
}
else
   obj.style.height=(parseInt(obj.style.height)-8).toString()+"px";
}
}
function showwin()
{
document.getElementsByTagName("html")[0].style.overflow = "hidden";
start();
document.getElementById("shadow").style.display="block";
document.getElementById("detail").style.display="block";
}
function recover()
{
document.getElementsByTagName("html")[0].style.overflow = "auto";
document.getElementById("shadow").style.display="none";
document.getElementById("detail").style.display="none";
}
</script>
</head>
<body onload="document.getElementById('tip').style.height='0px'">
<div id="shadow"> </div>
<div id="detail">

</div>
<div id="tip"><h1><a href="javascript:void(0)" onclick="start()">×</a>您有新消息</h1><p><a href="javascript:void(0)" onclick="showwin()">点击这里查看详细</a></p></div>
<p><a href="#" onclick="start()">点击这里测试</a><br><br><br><br>

</body>
</html>