Export WebGrid data to Excel in MVC4

I want to export WebGrid data to excel with formatting.

I have written below code which export WebGrid data to Excel.

 WebGrid grid = new WebGrid(source: listReport, canPage: false, canSort: false);

        string gridData = grid.GetHtml(
            columns: grid.Columns(
                    grid.Column("ID", "ID"),
                    grid.Column("Name", "Name"),
                    grid.Column("Summary", "Summary"),
                    grid.Column("Detail", "Detail"),
                    grid.Column("ProjectName", "Project Name")
                    )
                ).ToString();


        Response.ClearContent();
        Response.AddHeader("content-disposition", "attachment; filename=CustomerInfo.xls");
        Response.ContentType = "application/excel";
        Response.Write(gridData);
        Response.End();

I want to do formatting in excel. Is it possible to export data with formatting?

Also it gives me below error when i open the generated excel