Managing shared CSS and JavaScript values can be challenging, often leading to bugs when updates are required in multiple locations. A proposed solution involves using CSS environment variables and a PostCSS plugin to synchronize values between CSS and JS, allowing for a single source of truth. This method addresses common issues such as the limitations of inline styles and the maintenance risks of managing variables separately in CSS and JS files. By utilizing CSS env() and storing variables in a single JavaScript module, developers can streamline updates and reduce errors. This approach is particularly useful in complex projects where consistent styling responsiveness is crucial, as illustrated by the "Color Explorer" app scenario. While setting up this system may require initial effort, it promises long-term benefits by simplifying variable management and ensuring consistency across development environments.