When I add some description for ilustration in article , this ilustration is dislaing as large - should as minature.

When I delete that description, it looks fine.

This sounds like a template issue.
Without a link is impossible to tell, although you should address this issue to the template developer.

Please see:

www.new.ekopartner.org.pl/eko-wiadomosci/item/4608-kto-zbada-rolnictwo-ekologiczne
www.new.ekopartner.org.pl/eko-wiadomosci/item/4530-sejm-za-nowymi-regulacjami-dot-bezpieczenstwa-gmo-w-laboratoriach

Hello Michal,

This is a template issue indeed. You need to address this issue to the tempate developer.