<table></table>
tag is the preferable one.
It wont alter.try this one example
<table style="border-width:1px; border-color:Black ; border-style :groove ;"><tr>
<td><asp:label id="label1" name="User Name" runat="server" xmlns:asp="#unknown" /> </td>
<td><textbox id="textbox1" runat="server" /></td>
</tr>
<tr></tr>
</table>