Arthur Evain focused on enhancing accessibility in the lichess-org/lila repository by addressing a UI issue affecting blindfold chess mode. He implemented a targeted CSS fix using SCSS, ensuring that promotion pieces remained fully visible in the promotion chooser by overriding opacity settings. This solution resolved a visibility gap that previously hindered user experience for blindfold players, particularly during piece promotion flows. Arthur validated the fix across all relevant UI paths to prevent regressions, demonstrating careful frontend debugging and disciplined version control. His work contributed to a more accessible and user-friendly interface, leveraging his skills in CSS and front end development.