exportTo PNG not sizing chart consistently

I am trying to find a consistent way to export by gantt chart to png. My chart has a legend (header) which needs to be a fixed width. I would like the gantt to be the same width as the legend. It seems the size of the gantt depends on the monitor resolution, the size of the browser, etc. I would like to be able to produce exactly the same png for every user. Any ideas?

I might have found a solution:

		gantt.config.autosize = "x";
		gantt.config.autosize_min_width = 1625;

Seems to work.