use this ...may b this will help u
<table width="100%">
<tr>
<td align="Center">
<asp:Label ID="Lbldetails" runat="server" Visible="false" Height="197" BackColor="Black" ForeColor="GhostWhite" style=" size:auto; overflow:auto; width:246px"> </asp:Label>
</td>
</tr>
</table>