[DotNetDevelopment] export gridview to Excel; edit table style?

[okey]

I am exporting a gridview to Excel using

        var Response = HttpContext.Current.Response;
        string attachment = String.Format("attachment; filename=
{0}.xls", FileName.Replace(" ", string.Empty));
        Response.ClearContent();
        Response.AddHeader("content-disposition", attachment);
        Response.ContentType = "application/ms-excel";
        var sw = new StringWriter();
        var htw = new HtmlTextWriter(sw);
        gv.RenderControl(htw);
        Response.Write(sw.ToString());
        Response.End();

The string/file which Excel opens contains a table style element that
sets the background to black.  I want that white instead.  I tried
this at the top of the above snip  to try and locate the html element:

        for (int i = 0; i < gv.Controls.Count; i++)
        {
            var type = gv.Controls[i].GetType();
            if (type == typeof(Table))
            {


but never get a hit.  Do I have to manipulate the html string myself,
find <table style.....  and change the background value?  (I dumped
the file and <table style ... is there)

I also tried typeOf(System.Web.UI.WebControls.ChildTable), the closest
thing I could find to table, but I get an error:
System.Web.UI.WebControls.ChildTable' is inaccessible due to its
protection level

Thanks.