gtk applications & system/firefox fonts

Hi all!
By the way, sorry for my english...just lerning
Ok,i have some troubles with my favorite linux distributive. I use kde edition on my laptop dell inspiron.
I was a little bit confused after firefox looking in kde. It isn't to offend, but kubuntu has pretty good displayed firefox interface and (not sure, but...) type of fonts which looking more organicaly. In mageia 2 some fonts in firefox looks very fatly another ones very tiny or characters bump to each other. And the main firefox interface looks a little bit alien in kde. In comparison with kubuntu, where were included some special modifications for gtk2/3 applications. Anyway, kubuntu doesn't be compared with mageia in stability, kde-integrated and much more points
What do you do in firefox and system font settings, system tweaks for gtk?
What the best type of fonts for kde (in your opinion)?
it would be pleasure to see your screens with explanations
Thanks in advice!
By the way, sorry for my english...just lerning

Ok,i have some troubles with my favorite linux distributive. I use kde edition on my laptop dell inspiron.
I was a little bit confused after firefox looking in kde. It isn't to offend, but kubuntu has pretty good displayed firefox interface and (not sure, but...) type of fonts which looking more organicaly. In mageia 2 some fonts in firefox looks very fatly another ones very tiny or characters bump to each other. And the main firefox interface looks a little bit alien in kde. In comparison with kubuntu, where were included some special modifications for gtk2/3 applications. Anyway, kubuntu doesn't be compared with mageia in stability, kde-integrated and much more points

What do you do in firefox and system font settings, system tweaks for gtk?
What the best type of fonts for kde (in your opinion)?
it would be pleasure to see your screens with explanations
Thanks in advice!