Leonardo Color is a web-based tool designed to create and manage accessible color systems for user interface (UI) design and data visualization. The core architecture allows users to define color themes with precise control over color spaces, contrast ratios, and lightness. It enables the generation of color scales based on target contrast ratios, eliminating manual contrast checking. Adaptive themes facilitate quick changes to brightness, contrast, and saturation, including dark mode creation. The tool also supports colorblind-safe palette creation by automatically cycling through colors to ensure sufficient color difference or meeting a 3:1 contrast minimum. Integrations with design tools are streamlined through SVG downloads and CSS custom properties, with an npm module for end-user personalization. It's an open-source project by Adobe, fostering community contribution.