Adam McCartney enhanced the security of the environment banner in the DFE-Digital/login.dfe.help repository by implementing HTML sanitization and safe escaping within the layout. Focusing on both backend and front end development, Adam used JavaScript and ejs to mitigate XSS vulnerabilities that could arise from untrusted banner content. The solution ensures that environment messages are displayed as intended while preventing malicious input from compromising the login flow. By integrating these security measures, Adam improved the default safety of environment visibility across deployments, maintaining a seamless user experience and reducing exposure to common web security threats without introducing disruptive changes.