C# - Dynamically Adding A Styled Label To Web Page?

I have the following code which adds a label and a gridview to an asp.net page:

GridView grd = CreateGridView(kvp.Key.Text);
Label l = new Label();
l.Text = "some text";
l.CssClass = "this has no effect";
placeHolderResults.Controls.Add(l);
placeHolderResults.Controls.Add(grd);

Two questions really:As the page will have a multiple and unknow quantity of Label + Grid pairs I'm looping through the above code, is this the best way to add the controls to the page?I cannot style the label? How do you do it? Looking at the HTML which is created, the label turns out to be a SPAN.