Input background color not respecting Dark mode

Summary

(Summarize the bug encountered concisely)

Steps to reproduce

Background color is not Dark for the search input or password inputs on the below platforms.

Platform information

Windows 10 Firefox/Chrome Ubuntu Firefox.

What is the current bug behavior?

Background is white.

What is the expected correct behavior?

It should be dark.

Relevant logs and/or screenshots

From left to right

Windows 10 Firefox - Ubuntu Firefox - Ubuntu Chromium

Possible fixes

Probably some cross-browser CSS standards issue.

/label ~"T - Bug" ~"S - Triage:new"