How to style DetailsView control using CSS in ASP.Net

Try This

<asp:DetailsView ID="DetailsView1" runat="server" DataSourceID="SqlDataSource1" AutoGenerateRows="false" OnDataBound="DetailsView1_DataBound">
        <Fields>
          <asp:TemplateField>
            <ItemTemplate>
              <table id="Table1" runat="server" width="400" cellpadding="0" cellspacing="0">
                <tr height="50">
                  <td width="33%" align="center">Name:<asp:Label runat="server" ID="l1" Text='<%# Eval("Name") %>'></asp:Label></td>
                  <td width="33%" align="center"></td>
                  <td width="33%" align="center">Phone:<asp:Label runat="server" ID="l2" Text='<%# Eval("Number") %>'></asp:Label></td>
                   </tr> 
                   <tr height="50">
                  <td width="33%" align="center">Description:<asp:Label runat="server" ID="Label1" Text='<%# Eval("Description") %>'></asp:Label></td>
                  <td width="33%" align="center"></td>
                  <td width="33%" align="center">Amount:<asp:Label runat="server" ID="Label2" Text='<%# Eval("Amount") %>'></asp:Label></td>
                   </tr>
              </table>
            </ItemTemplate>
          </asp:TemplateField>
        </Fields>
</asp:DetailsView>