"Your shirt is black."
Translation:Το πουκάμισο σου είναι μαύρο.
Yes, it should. The contributors are aware of this, once they are allowed to edit the (currently locked) Greek sentences they''ll fix this. Please remember that the course is in beta, mistakes and omissions are to be expected during this phase. :) But it's good that you're mentioning it as more users who might not know about this rule will see it.
What is "τοπ"? I have NEVER seen it before and even Duolingo's dictionary doesn't recognize it ... I got the right answer in the exercise just because all the other options were wrong ... I have seen just now the answer of Georgopoulos but it has not been fixed yet ...