I'm noticing (small but annoying) issues in the vertical aligment of texts inside tag boxes, since the switch to the new system fonts. I'm using Chrome 90.0.4430.212 with Windows 10.
In this example, the tags "elementary-number-theory" and "decimal-expansion" seem to lay closer to the bottom than the "partial-differential-equations". And indeed they are, by one pixel. The CSS seems to be all right, the problem seems to be in the font itself.