A bathroom is usually the smallest room in the house, but it doesn’t mean it can’t be colorful. If you have a small windowless bathroom, you can easily incorporate some bold and bright colors to open up the space and create an illusion of a well-lit room. There are many paint color options as long as you know which works best with your small bathroom. A bathroom is usually the smallest room in the house, but it doesn’t mean it can’t be colorful. If you have a small windowless bathroom, you can easily incorporate some bold and bright colors to open up the space and create an illusion of a well-lit room. There are many paint color options as long as you know which works best with your small bathroom.