Accelerating GitHub theme creation with color tooling

Dark mode has transitioned from an optional feature to a user expectation, yet implementing it remains challenging for many teams, particularly when creating multiple themes. GitHub's dark mode, revealed in December 2020, was developed through a complex process involving extensive trial and error and the use of a Figma file with over 370,000 layers. To streamline future color palette creation, GitHub developed Primer Prism, an experimental tool that is part of GitHub's Primer ecosystem, aimed at creating cohesive, consistent, and accessible color palettes. Primer Prism allows users to define tones, choose colors, and test them by adjusting lightness curves and ensuring perceptual uniformity using the HSLuv color space. This tool facilitates the creation of dark high contrast, light high contrast, and colorblind themes for GitHub by allowing easy adjustments and visual testing, with plans for further integration with GitHub and Figma. Primer Prism is open source and invites user feedback, though it remains in an experimental phase prone to bugs and changes.