The genus Abax is definitely right, but I can't see any rugose punctures in the basal half of the pronotum, which would be the key character for A. carinatus.
http://www.kerbtier.de/cgi-bin/deXCompare.cgi?ID=e7352377b2
I think it's rather another Abax species, but I'm not sure which one. The ones shown on this website are from Germany. Croatia has a slightly different fauna, with a few more species. A. parallelepipedus is the most common one.
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