Changing the Datagrid Header Colour in Pdf

private void button1_Click(object sender, RoutedEventArgs e)
       {
           ExportPdf(pdftbl);
       }

public void ExportPdf(DataTable dt)
        {
            Document document = new Document();
            PdfWriter writer = PdfWriter.GetInstance(document, new FileStream("C://Bala//testpdf.pdf", FileMode.Create));
            document.Open();
            iTextSharp.text.Font font5 = iTextSharp.text.FontFactory.GetFont(FontFactory.HELVETICA, 5);
            PdfPTable table = new PdfPTable(dt.Columns.Count);
            PdfPRow row = null;
            float[] widths = new float[] { 4f, 4f, 4f };
            //Creating Header Color Change
            PdfPCell CellActext = new PdfPCell(new Phrase(new Chunk("Name", FontFactory.GetFont("Arial", 8, iTextSharp.text.Font.BOLD, iTextSharp.text.Color.GREEN))));
            CellActext.Colspan = 1;
            CellActext.Border = 0;
            CellActext.HorizontalAlignment = Element.ALIGN_LEFT;
            CellActext.BackgroundColor = new iTextSharp.text.Color(24, 150, 191);
            table.AddCell(CellActext);
            PdfPCell CellActext1 = new PdfPCell(new Phrase(new Chunk("Age", FontFactory.GetFont("Arial", 8, iTextSharp.text.Font.BOLD, iTextSharp.text.Color.ORANGE))));
            CellActext1.Colspan = 1;
            CellActext1.Border = 0;
            CellActext1.HorizontalAlignment = Element.ALIGN_LEFT;
            CellActext1.BackgroundColor = new iTextSharp.text.Color(25, 140, 181);
            table.AddCell(CellActext1);
            PdfPCell CellActext2 = new PdfPCell(new Phrase(new Chunk("SecondName", FontFactory.GetFont("Arial", 8, iTextSharp.text.Font.BOLD, iTextSharp.text.Color.BLUE))));
            CellActext2.Colspan = 1;
            CellActext2.Border = 0;
            CellActext2.HorizontalAlignment = Element.ALIGN_LEFT;
            CellActext2.BackgroundColor = new iTextSharp.text.Color(23, 130, 111);
            table.AddCell(CellActext2);
            table.SetWidths(widths);
            table.WidthPercentage = 100;
            int iCol = 0;
            string colname = "";
            foreach (DataColumn c in dt.Columns)
            {
              table.AddCell(new Phrase(c.ColumnName, font5));
            }
            foreach (DataRow r in dt.Rows)
            {
                if (dt.Rows.Count > 0)
                {
                    table.AddCell(new Phrase(r[0].ToString(), font5));
                    table.AddCell(new Phrase(r[1].ToString(), font5));
                    table.AddCell(new Phrase(r[2].ToString(), font5));
                }
                } 
           document.Add(table);
           document.Close();
        }