Use A Black Background
To Intensify Colors
The same colors look richer and more intense when they are on a black background. On the white background they are quieter, more laid back.
Dark brown has a lot of black in it, so it too intensifies colors
The same goes for dark purple.
Any dark color that approaches black when used as a background will make other colors richer and more vibrant. However, black does it best.
Red and Green OP 4, 5
4 hours ago