A powder room is small, windowless, and forgiving, which makes it the best room in the house to commit to a real color. This palette puts a muted, slightly gray Olive Grove on every wall, the kind of green that goes earthy and grounded under warm bulbs instead of bright or minty.
To keep it from feeling heavy, the vanity and backdrop wear a Soft Linen and the trim and ceiling stay Crisp White, so the olive has a clean edge to lean on. Warm Oak on the floor and a floating shelf brings in the wood tone that olive always wants beside it.
For the one bit of drama, a Burnt Clay mirror frame gives the eye a warm, reddish anchor against all that green. Use that deepest color on the smallest surface only, one frame or one sconce, and let the olive carry the room.