So in Croatian traditional literature and fairy tales devil is always black. But in all the modern western cartoons devil is red. Why is this so? Do other European tend to portray it in red?
This is how Dante Alighieri described Satan in the Divine Comedy, which he wrote in the early 14th century. This is from the Everyman edition, translated by Allen Mandelbaum.
If he was once as handsome as he now is ugly and, despite that, raised his brows against his Maker, one can understand how every sorrow has its source in him! I marvelled when I saw that, on his head, he had three faces: one - in front - bloodred; and then another two that, just above the midpoint of each shoulder, joined the first; and at the crown, all three were reattached; the right looked somewhat yellow, somewhat white; the left in appearance was like those from where the Nile, descending, flows. Inferno, Canto 34
So redness has some long association with the popular image of Satan, but it seems we've abandoned the portrayal of him with 3 faces.
Take note OP, that "Devil" and "Satan" are not exactly the same thing. Slavic (and thus, Croatian) folklore includes "devils" which are usually black/darkish, hairy, horned and hoofed tricksters (slighlty similar to fauns/satyrs). Elements of this creatuyre were incorporated in the folk-christian "Devil", the same way as the legend of upyr was hammered into the gothic tale of a vampire.
The modern depiction of "the Devil" is a mixture of the red-faced and evil fallen angel of christian mythology, with the horned and hoofed, trickster-ish spirit of Slavic folklore.