怎么样才能使table垂直与水平居中?
<%@ Page language="c#" Codebehind="login.aspx.cs" AutoEventWireup="false" Inherits="Webs.login" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<title>系统登录</title>
<meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR">
<meta content="C#" name="CODE_LANGUAGE">
<meta content="JavaScript" name="vs_defaultClientScript">
<meta content="http://schemas.microsoft.com/intellisense/ie5" name="vs_targetSchema">
</HEAD>
<body>
<div align="center">
<form id="Form1" method="post" runat="server">
<FONT face="宋体"><INPUT id="errormessage" style="Z-INDEX: 101; LEFT: 8px; WIDTH: 96px; POSITION: absolute; TOP: 8px; HEIGHT: 22px"
type="hidden" size="10" name="passTxt" runat="server"></FONT>
</form>
<TABLE id="Table1" align="center">
<TR>
<TD style="WIDTH: 53px; HEIGHT: 24px"><FONT face="宋体"><FONT face="宋体">
<asp:label id="Label1" runat="server" Font-Size="X-Small">用户名</asp:label></FONT></FONT></TD>
<TD style="WIDTH: 137px; HEIGHT: 24px">
<asp:textbox id="TextBox1" runat="server"></asp:textbox></TD>
</TR>
<TR>
<TD style="WIDTH: 53px"><FONT face="宋体">
<asp:label id="Label2" runat="server" Font-Size="X-Small">密码</asp:label></FONT></TD>
<TD style="WIDTH: 137px">
<asp:textbox id="TextBox2" runat="server"></asp:textbox></TD>
</TR>
<TR>
<TD style="WIDTH: 53px"><FONT face="宋体"></FONT></TD>
<TD style="WIDTH: 137px"><FONT face="宋体">
<asp:ImageButton id="ImageButton1" runat="server" ImageUrl="images\LOGIN.GIF" Height="24px" Width="44px"></asp:ImageButton></FONT></TD>
</TR>
</TABLE>
</div> </body>
</HTML>
我只能做到水平居中;但不能垂直居中