Thank you again. I confess I had never conceived of a colour as a noun. As for adverbial phrases, I am sure millions of native French get along fine without ever having heard the term. Would that we ancients could soak up a tongue as a child does.
Well, I was thinking blue and white were not nominatives but adjectives describing the elided [la couleur]. So how would the F go if the E was "available in the color blue or the color white?" I guess we have to live with the reality that "Le bleu est une couleur."