Start with Midnight Navy on the walls and the whole little room turns into a jewel box. Deep, inky blue feels rich and calming, and because a powder room is small you can go this dark without it ever feeling heavy. By candle or a single warm light it reads almost black, then shows its true blue in daylight. It is the kind of color that makes guests pause and look twice, which is exactly what you want in the one room everyone visits.
Against that depth, Soft Gold does the glamour work. Use it in small, shiny doses, on a mirror frame, the faucet, a light fixture, so it catches the light and warms the cool navy up. Then Warm White keeps it from feeling too closed in, brightening the trim, the ceiling, and any millwork so the navy has a crisp edge to lean on. In short, navy on the walls, white on the trim and ceiling, and gold saved for the fixtures and accents that sparkle.