Use lowercase letter sizing?
font-size-adjust
Use the height of the lowercase letter "x" to determine the font size rather than the size of the uppercase letter "X".
Property values
Specify a number to be used as a multiplier against the element's font-size property. The result is used to pick a font whose size matches the height of the letter "x".
Examples
/* pick a font whose letter "x" is 6.5pt high */
font-size: 13pt;
font-size-adjust: 0.5;