Sungjeon Choi enhanced navigation and user interface components across the GSA/USSM and GSA/eoc repositories, focusing on developer productivity and content readability. He reorganized side navigation in GSA/USSM by introducing new sections with gradient styling and improved header structure, using CSS and SCSS to refine the visual hierarchy. In GSA/eoc, he increased text container height and adapted layouts to better support guidance links, while also upgrading a Ruby gem dependency for improved stability. His work addressed maintainability and consistency, applying configuration management and front end development skills to deliver low-risk, well-structured improvements that support future feature development.