Worked on the BlockNote repository to deliver a major user experience improvement for mobile by building a flicker-free formatting toolbar. The solution replaced React state-driven positioning with CSS custom properties, eliminating unnecessary re-renders and reducing visual jitter during keyboard interactions. Leveraging TypeScript and CSS, the implementation introduced a two-tier keyboard detection system using the VirtualKeyboard API and Visual Viewport fallback, ensuring accurate toolbar placement across browsers. Additional enhancements included auto-scrolling selected content into view, optimizing touch interactions, and handling device-specific safe area insets. This work improved accessibility and usability, demonstrating a strong focus on front end development and cross-device reliability.