为什么这段代码会在 google chrome 的页面顶部留下一条白条?
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>title goes here</title>
</head>
<body style="margin:0px 0px 0px 0px;padding:0px 0px 0px 0px">
<form id="form1" runat="server" style="padding:0px 0px 0px 0px;margin:0px 0px 0px 0px">
<div style="background-color: blue;">
<p> </p>
</div>
</form>
<p> </p>
</body>
</html>