"¿Tú tienes un vestido rojo?"
Translation:Do you have a red dress?
"Have you a red dress" is the same as "Do you have a red dress" yet it was marked wrong???
You are correct it is proper. However, here in America at least, "Have you a red dress" sounds a little stilted and not likely to be used in conversation.
I have been forced to tolerate DL's annoying use of the redundant "got" everywhere. The least they can do is accept it when I leave it out. "Have you a red dress" is perfect English and an accurate translation. It is not "wrong"!!!
"You've one red dress?" doesn't make too much sense. The "Do you have a red dress?" was supposably an incorrect submission.