                       type: 'pattern',
                        pattern: 'solid',
                        fgColor: {
                            argb: isHeader ? 'FF545454' :
                                isLastRow ? 'FFFFE599' :  // light yellow
                                'FFF5F5F5'
                        }
                    };

                    excelCell.border = {
                        top: { style: 'thin' },
                        left: { style: 'thin' },
                        bottom: 