...

Question

Cette question peut être bête mas, pourquoi est noir féminin? La Dame en Noir a hanté cette maison depuis des siècles? Merci

Answer

[person] noir(e)
⇒ She's black. Elle est noire.
I am not finding the noir reference in the lesson listed with your question.

Answer

Bonjour Daniel !

That's a great question, and the answer is simpler than it seems :)

Here it's not the woman who's black, but her clothes = in black (clothing).
Therefore, the adjective won't agree here: "en + [masculine colour]".
"La Dame en noir / en blanc / en vert..."
It would be the same in sentences such as:
"J'aimerais cette jupe en violet."  (I'd like this skirt in purple.)

I hope that's helpful!
À bientôt !