The original work on improving and unifying button appearance and CSS was accompanied with a certain combination of workarounds to make up for a Firefox/macOS rendering quirks:
When font family is set to generic sans-serif, Firefox (at least for the last 20+ versions, with current version being v65) seems to use “Helvetica Neue” for it.
But it applies a different line-box when applying sans-serif than all other major browser on macOS (Chrome, Safari) ending up in a lower than expected base line:
Reduced code example:
This has led me to implement different top/bottom paddings with an uneven line-height, but it was a bad choice for further cross-browser consistent rendering and also for code size.
We need to unify paddings and line-height to more sane values.