This blog used to set its font size as 85% of the user's specified font size. People complained about not being able to read comments on large screens, but I didn't see a way to change the font size for some and not adversely impact others. dmarkle pointed out that using points would be portable across resolutions as 72pt = 1 inch. With that knowledge, I changed this site to use an 10pt font.
If there's a font legibility issue, let me know.