Thick Boundary Lines Issue

This is just an annoying cosmetic issue, but something you should put on your list to fix.  As you can see in the screen snapshot below, the thick boundary lines do not match-up with the colors of the underlying cells. When you zoom all the way in, the boundary lines will gradually move to the correct position when you are zoomed all the way in, but as you zoom out, the boundary lines gradually move to the incorrect position.