font-size-adjust CSS property to the value corresponding to main text font.
Other fonts will be adjusted so that lower letters will be of equal height.
The value may need some tuning, especially at small sizes.
This page calculates aspect ratio of various common fonts.
<canvas> to measure proportion 'x' letter height to the em box (x-height in ems).
Depending on browser, missing fonts may be replaced with surrogates and yield wrong value.
font-size-adjust property is supported by Firefox.