How to freeze header and column when grid view exported to excel using openxml

public static void ExportMehod(GridView gvde, string excelName, string Sheetname)
        {

            try
            {
                string MethodName = "ExportToExcel_Open_XML(GridView gvde,string excelName, string excelName)";
                using (OfficeOpenXml.ExcelPackage pck = new OfficeOpenXml.ExcelPackage())
                {
                    HttpResponse Response = System.Web.HttpContext.Current.Response;
                    OfficeOpenXml.ExcelWorksheet ws;
                    ws = pck.Workbook.Worksheets.Add(Sheetname);
                    ws.View.FreezePanes(4, 3);
                    Response.Clear();
                    Response.Buffer = true;
                    Response.AddHeader("content-disposition", "attachment;filename=Delivery_excellence_Dashboard.xls");
                    Response.Charset = "";
                    Response.ContentType = "application/vnd.ms-excel";
                    gvde.HeaderStyle.BackColor = Color.Black;
                    gvde.HeaderStyle.ForeColor = Color.White;
                    using (StringWriter sw = new StringWriter())
                    {
                        HtmlTextWriter hw = new HtmlTextWriter(sw);
                        //To Export all pages
                        gvde.AllowPaging = false;
                        gvde.RenderControl(hw);
                     
                        //style to format numbers to string
                        string style = @"<style> .textmode { } </style>";
                        Response.Write(style);
                        Response.Output.Write(sw.ToString());
                        Response.Flush();
                        Response.End();
                    }
                }
            }
            catch (Exception ex)
            {
                Errormsg = ex.ToString();
            }
        }