A room with chair rail on only 3 walls?

Looking for some color inspiration, and got myself involved in painting the whole house, now, when it started with crown in the kitchen.Chat Icon Chat Icon Chat Icon

Back wall of room is cathedral, and painted a gray/green, mid tone color, chair rail goes around the 3 other walls....and the top is already an almond color...

looking for a dark color for botton half of walls,

but can that color be darker than the accennt wall, no right???