Global Dark Style for Chrome and Firefox applies a dark theme to websites via a toggleable icon.

One nice thing included is if a website has a built-in dark theme, which you prefer over the one that this extension/add-on offers, you can add the target website's hostname to the blacklist to prevent the extension from applying the rules.

Since there is no way to provide global rules that look good on all web pages, this extension offers a per-site rules section. Here, you can add additional rules for a single hostname. Also, it is possible to append the global rules that will be applied to all hostnames. It can also be globally inactive just by clicking the icon once. The next click will enable the extension.

Global Dark Style is simple to use for those that like a dark theme for their browsing but will also be useful during low light sessions. And it is designed to be low resources as it uses a non-persistent background page, which prevents resource usage when it is inactive.

Global Dark Style Features:

A clean small CSS based rules to darken the web

Toggle on and off from the toolbar button

Supports blacklist to add hostnames to the exception list

Supports per-domain rules to adjust the default theme per hostname

Similar:

How to Enable Dark Mode in Windows 10

How to Enable Dark Mode for All Sites in Microsoft Edge

Enable Night Light Mode in Windows 10 to Reduce Eye Strain

How to Turn the Windows 10 Desktop Background Image On or Off