Penumbra

Penumbra is a mathematically balanced color scheme designed in a perceptually uniform color space, with base colors inspired by the natural interplay of sunlight and sky. It separates luminance, chroma, and hue to make the most efficient use of the available color space on standard electronic displays. The palette consists of nine nearly symmetric base colors, which are used to build the main light and dark themes, along with two additional high-contrast dark variants tailored for people with mild to moderate visual impairments. Its design focuses on functionality first, while maintaining an aesthetic quality that draws from familiar natural tones. Beyond its use in text editors and terminal environments, Penumbra’s carefully structured accent palettes are also suited for encoding information in data visualizations, where perceptual uniformity and hue differentiability are critical.