Diacritic marks ugly in Firefox

[witek]

I have very ugly fonts with diacritic marks in Firefox on some websites. Can anybody advise how to change it?

[p-472]

Maybee you change you character encoding in Firefox.
You can find it under view. top right at the settings.

Witch version of Firefox you use ? Firefox, Firefox-esr or the new one Firefox 57 ?

[witek]

Firefox ESR. Encoding is OK. Diacritics are much smaller than regular characters.
It seems to happen on websites that don`t force their own fonts. These problematic fonts are not anti-aliased or hinted. Other websites work OK. I tried to change the default font in Firefox but it won`t help. Here how it looks like:

[pavroo]

Change the screenshot, please.

[witek]

Change the screenshot, please.

What do you mean? Anyway, the image is here: http://advamacs.pl/pub/fonts.png

[witek]

Firefox 57 also spoils diactritics on some websites. Any ideas, please?