FrenchKing makes the point.
In addition that is the color what you like is poor English.
Nothing wrong with poor English except that isn't what Duo wants to teach.
C'est la couleur que tu aimes. This is also correct if you know the subject well?
Hello! I'm pretty tired right now, but i'm struggling to see why this is a question?
The tone of voice if it was a person saying it instead of the Duo machine.
The question mark if it is a written example you were translating.