I'm not a designer nor I have a major in typography, so the following is a pure subjectivism.
I think that half-measures are evil, and attempting to fit subscripts in chemical formulas with the oldstyle/hanging numbers is a half-measure. The web is still crippled in typographic features compared to the desktop publishing systems, but it's not an excuse for a poor font choice. I call it poor because every time I see numbers in Georgia not lining up, "The Adventure of the Dancing Men" comes to my mind.
Some time ago I did comparison tables for the cherry-picked free and open source fonts alongside with the default fonts installed in Windows that don't look particularly ugly:
My main concern at the time I compiled these tables with XeLaTeX was to find the font that has better coverage for the symbols used by chemists and to find a font family of the sans-serif fonts where one can actually distinguish between I
and l
in chemical formulas (on the side note, I still think that choosing Arial as the default font by ACS for representing drawn formulas was a big mistake resulting in the urge to use lowercase letter "ell" instead of semantically correct lowercase "l": $\ce{HC\ell}$ vs $\ce{HCl}$).
Back to the main issue, as long as there is MathJax used, it feels like the main font should be a serif font to comply with Computer Modern (or its derivative) used by it. Among the serif fonts I personally find these three open fonts sticking out:
- STIX Two/XITS. Made specifically for scientists, based on Times ligatures. One of the few fonts offering the proper
⦵
symbol for the standard state. With a recent 2.0 release there were major improvements.
- Linux Libertine. Mature, looks fairly good, great coverage. Used by Wikipedia, nuff said.
- Noto Serif. Covers lots of symbols, installed by default in all modern systems. However, not looking scientifically enough to my eyes.
Also, Georgia font has very rudimentary ligatures support, and some titles are just painful to look at. The majority of other fonts do it better, and of course, the above mentioned fonts handle ligatures much better:
To sum it up: I think the numbers should be lined, serif font is better, and among serif fonts either STIX or Linux Libertine (or their derivatives, e.g. XITS or Linux Biolinum) would be arguably the best option. And no, I don't like Georgia [font].