Ahh. Okay, mystery solved. I have my minimum font size set to 18. Because of that, Firefox renders all four digits at the same size. It also does not superscri

Ahh. Okay, mystery solved. I have my minimum font size set to 18. Because of that, Firefox renders all four digits at the same size. It also does not superscript the last two digits. I just checked, and it's the same in Safari. One could expect that, even if minimum font size is set, that the concept of "superscript" would survive, i.e. that the digits "19" would be rendered above the typographic baseline. One could expect that, but one would be wrong. :)