Export ASP.Net GridView with Background colors to PDF using iTextSharp

Hi,

i want  print gridview in pdf format .print successfull but print without background color, header ,coloumn, and row

 i am using following code :

 protected void Button3_Click(object sender, EventArgs e)
    {
        Response.ContentType = "application/pdf";
        Response.AddHeader("content-disposition", "attachment;filename=Govind.pdf");
        Response.Cache.SetCacheability(HttpCacheability.NoCache);
        StringWriter sw = new StringWriter();
        HtmlTextWriter hw = new HtmlTextWriter(sw);
        GridView1.ShowHeader = true;
        GridView1.AllowPaging = false;
        SqlCommand cmd = new SqlCommand("Select top 10 * from   tbl_StudentRegistration", con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        GridView1.DataSource = ds;
        GridView1.DataBind();
        GridView1.RenderControl(hw);
        GridView1.HeaderRow.Style.Add("width", "15%");
        GridView1.HeaderRow.Style.Add("font-size", "10px");
        GridView1.Style.Add("text-decoration", "none");
        GridView1.Style.Add("font-family", "Arial, Helvetica, sans-serif;");
        GridView1.Style.Add("font-size", "8px");
        StringReader sr = new StringReader(sw.ToString());
        Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);
        HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
        PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
        pdfDoc.Open();
        htmlparser.Parse(sr);
        pdfDoc.Close();
        Response.Write(pdfDoc);
        Response.End();
    }

Thanks & Regards

 Govind Jangir