Celeste Pan focused on maintaining and improving the CSS Masonry test suite within the mozilla/gecko-dev repository over a two-month period. She addressed test reliability by aligning test file naming conventions and updating references to ensure correct execution in continuous integration environments. Using her expertise in CSS, HTML, and web-platform testing, Celeste expanded test coverage to capture layout differences across item-tolerance values and refined existing tests for clarity and maintainability. Her work did not introduce new features but instead prioritized test hygiene and stability, reducing the risk of flaky failures and supporting future development of the CSS Masonry implementation.