Add Custom Admin CSS

How can you add custom admin css in WordPress? This use case shows how a focused WordPress code snippet can handle the task without installing a heavy plugin. The snippet should load a custom admin CSS file and produce this result: The WordPress admin area uses the custom CSS rules from the theme or plugin. You can also log in to LeonLab.ai, describe this WordPress use case in plain English, generate the snippet, review the PHP code, and deploy it to the selected WordPress project.