PDF Export with .timeline_cell CSS

Gantt
#1

Hi,

I am trying to export gantt chart to PDF with weekend dates marked with grey background.
This works fine when using exportToPDF with RAW: TRUE but we need to use RAW: FALSE and that’s not working.

Is there any way to do this ?

gantt.exportToPDF({
    raw: false,
    header: "<style>" + document.getElementById("styles").innerHTML + "</style>"
});

Template:
gantt.templates.timeline_cell_class = function (task, date) {

          if (date.getDay() === 6) {
                  return "week_end";                
            } else if (date.getDay() === 0) {
                return "week_end";                
            } else {
                return ;
            }

};

CSS:
.gantt_task_cell.week_end {
background: #f2f2f2;
border-bottom: 1px solid #cecece;
border-right: 1px solid #cacaca !important;
}

See example:
https://snippet.dhtmlx.com/0t5jzq0e