Custom Admin CSS is for a dashboard adjustment you can express directly in CSS: a spacing change, a targeted visual correction, or a short set of client-specific rules. Save the stylesheet in the module and it is printed inline across wp-admin. Choose selectors carefully because a broad rule can affect several screens, not just the page you had open while writing it. There is no visual selector or per-role rule builder; the stylesheet itself determines what is targeted.

The module removes tags and selected unsafe constructs, including script markup, javascript: URLs, expression(), behavior:, and data-URL patterns. This filtering does not guarantee that every accepted rule will be visually harmless. For palette changes, Admin Color Customizer provides a dedicated scheme workflow. For the sign-in screen, use Login Page Customizer instead: this module never styles login or public pages. Keeping those surfaces separate makes the saved admin CSS easier to understand and maintain.