Test yourself on the Colours.
Nouns in Croatian have a gender, and adjectives have to agree with the noun.
This is the same when using the colours in Croatian. Mačka 'cat' is a feminine noun, and pas 'dog' is masculine.
The Croatian word for black is crni or crna depending on the noun.
Crna mačka 'black cat' and crni pas 'black dog'.