Karl Rehnström contributed to Forsakringskassan’s docs-generator and designsystem repositories by delivering targeted UI improvements and enhancing theming maintainability. He implemented code snippet rendering within MessageBox components, refining their visuals and standardizing styling through the introduction of CSS variables and SCSS. In the designsystem repository, Karl replaced direct CSS variables with SCSS-based semantic tokens for tooltip theming, enabling more scalable and maintainable design systems. He also addressed visual inconsistencies by fixing modal shelf colors to ensure uniform presentation. His work demonstrated a thoughtful approach to front-end development, focusing on maintainable code and consistent user interfaces using JavaScript, SCSS, and CSS.