With the increasing support for Dark Mode in operating systems and browsers, web developers are encouraged to accommodate both light and dark appearances in their applications. This involves utilizing CSS media queries to specify styles based on the user's OS color scheme preference, and best practices suggest separating these styles into distinct stylesheets to minimize download size. Testing these appearances can be efficiently managed using tools like Cypress, which allow for forced Dark Mode testing via browser flags and JavaScript. However, forcing Light Mode isn't as straightforward, necessitating workarounds such as using JavaScript to dynamically load stylesheets based on media queries. This approach enables comprehensive testing of both light and dark modes, ensuring that web applications maintain aesthetic and functional integrity across different user preferences. Additionally, integrating accessibility color tests and incorporating appearance checks into smoke tests can further enhance the robustness of an application's design across varying display modes.