Jesper contributed to the HGustavs/LenaSYS repository by standardizing UI shadows and centralizing color filters using CSS and front-end development skills. He refactored box-shadow definitions to use dedicated CSS variables, improving maintainability and enabling faster theming while reducing visual inconsistencies across the interface. Jesper also addressed a critical UI bug by consolidating the purple icon color filter into a single CSS variable, eliminating duplication and streamlining color transformation logic. His work focused on enhancing design consistency and reducing the risk of regressions, demonstrating a methodical approach to maintainable styling and thoughtful use of CSS for scalable front-end solutions.