>>212621548
In Bosnia all ethnicities have individuals which could pass as Poles.
Some of the oldest roman writings of Slavs describe them as having commonly darker shades of hair compared to Germanic people at least but still fair skin. Keep in mind that a lot of Poles have German blood and ancestry while Russians have a lot of Finnic and Viking as well.
The largest group of brown Croats here are some kind of assimilated vlachs commonly found in Dalmatia which are darker than the average swarthy herzeg.