"The rabbit is white and brown."

Translation: Het konijn is wit en bruin.

[Helen512874]

What about: "Het konijn is wit met bruin?"
It was marked wrong, but why?

[Judas.bh]

Do adjectives that do not directly modify a noun never take the -e ending?

[vam1980]

In this case 'wit' and 'bruin' are predicate adjectives. Predicate adjectives never get the -e. See also: https://www.duolingo.com/comment/3888221