I would paint it the color of the walls. If you paint it using the color of the ceiling it will draw even more attention to it. I think it would look less obtrusive if it blended with the walls.

Same colour as the walls.

Wall

wall

Same as the walls

definitely the color of the wall

I'd paint the walls and ceiling the same color in this small space -- will make it less obtrusive overall.

That is what I would do all one color.

Yes, all one color, bulkhead disappears and you can pretend it isn't there!