Dear @EvaAnna
It could be to do with you using 'px' pixels for your 'font-size' settings, on different machines/screen this can be affected.
In text formats changing to a 'font-size: % ' may have some results:
Screen Shot 2020-12-08 at 5.52.04 PM.png
Further you could force them with Custom CSS and set font-size: to 'em' or "rem'
https://www.w3schools.com/cssref/css_units.asp
Hope this helps @EvaAnna, website looks awesome BTW :)
Best
Richard