add wood wallpaper to the kick plates of the stairs. Those rolls are expensive but you would only need one. Not practical with white treads though, it will be stuffed up from black shoe soles in no time.
A Well-Curated Home: Isay Weinfeld Designs Casa Cubo
On the stair is the Floor Paint regular. You can use it without a primer. Easy to apply and looks perfect. On the walls our Chalk Paint in the color Evening Shadow and the doors in Lacquer full Gloss color Silk White.