title: Force line height in gridview
body: <p>I have a GridView with template fields and labels in its item template. The height is set to be 12px through CssClass. (line-height=12px;height=12px). Everything works the way that I expect.</p>
  
  <p>Once I give visibility to a TextBox, than the line height increases by approximately 1px per row, even though I reduce the height of the Textbox to a hypothetical 5px.</p>
  
  <pre><code>&lt;asp:templatefield HeaderText="Result" ItemStyle-HorizontalAlign="center"&gt;
      &lt;ItemTemplate&gt;
          &lt;asp:Label runat="server" Text='&lt;%# Bind("Result") %&gt;' id="LabelResult" CssClass="NarrowGrid" visible="false"/&gt;
          &lt;asp:TextBox runat="server" id="TextBoxResult" Height="5px"  Width="25px" Visible="true" CssClass="NarrowGrid"/&gt;
      &lt;/ItemTemplate&gt;
  &lt;/asp:templatefield&gt;
  </code></pre>
  
  <p>How can I achieve/force 12px to be the line height in both cases?</p>