Worked on the microsoft/fluentui-contrib repository to enhance theming flexibility and improve CSS variable reliability within the Griffel integration. Focused on front end development using React and TypeScript, the work involved extending the CAPThemeProvider component to allow broader theme customization while maintaining backward compatibility for existing themes. Addressed a persistent issue with CSS variable name escaping by updating the formatCAPTokenCssVar utility, replacing slashes with dashes to ensure proper handling of design tokens in Griffel. This combination of feature development and targeted bug fixing contributed to a more robust and customizable theming system for downstream consumers of the library.