Worked on improving cross-browser UI reliability for the mui/base-ui repository, focusing on navigation components. Addressed a Safari-specific issue where the navigation menu positioner’s width was incorrectly computed on hover, leading to inconsistent visual behavior. The solution involved ensuring accurate measurement and application of width and height for the positioner element, implemented using React with JavaScript and TypeScript. Added comprehensive regression tests to verify correct handling of the positioner’s dimensions across multiple scenarios, enhancing quality assurance readiness. Maintained API stability by introducing only non-breaking changes, resulting in a more consistent navigation experience and improved design parity across browsers.