:autofill and the colors imposed by the browser

Useful to know

:autofill selects a field whose value is automatically filled in by the browser. After the user edits it, this state may cease to match. [1]

When shaping, don't assume that a simple background rule will prevail. Autofill browser styles sometimes use !important and limit the replacement of certain colors. Try real saved data in the target browser instead of just manually typed text. Maintain readable labels and contrast, regardless of which color remains. The goal is a clear form, not a disguise of the useful autofill.