@TomMalbran, okay, sounds good.  Thanks for addressing all my questions.

@RaymondLim, I tested the code setting the font size to em units.  It works; however, as @TomMalbran and I were discussing, that branch of the code never gets run.  Currently, all font sizes contained in variables `oldFontSize` and `newFontSize` are always in terms of pixels.  I addressed your question on the math of em ratios as best I could so I think this code review is done.  I have nothing to change in the code at this point.