Color theory
Black, white, and the space between
Neutrals are not empty space. They set the scale, temperature, and breathing room that let expressive colors become legible.
A neutral still has a temperature
Pure black and pure white are useful extremes, but most working neutrals carry a trace of another hue. A warm grey can soften a palette; a blue-grey can make the same interface feel more precise and distant.
That trace is often what makes a neutral sit comfortably beside the rest of the system. Choose it in context instead of selecting grey as an afterthought.
Use contrast as a material
Neutrals create hierarchy through value. Reserve the deepest tone for structure and high-priority text, then let lighter surfaces separate layers without adding more hue.
When the expressive colors enter, they should have somewhere to land. The quiet parts of the palette are what make an accent feel intentional rather than merely bright.