Font size changes the wrong way

Hey, I’m very confused with how to change the font size.

This is how the font looks with size 11px: https://ibb.co/qs8fTb1
and this is 12px: https://ibb.co/R3jrVrk
12px is smaller

It’s not only in the editor though. This is how they look when I send a test to my email:
11px: https://ibb.co/N7cMM5x
12px: https://ibb.co/jMMFQK2
Maybe it’s not very clear on these screenshots but it’s basically the same: 11px looks bigger than 12px

It’s a great, very clean and clear plugin which I find super useful but this thing about font has been confusing me so much. Please help! ??