Custom Dark Mode is a browser add-on that help you design your own dark style for the web.
Simply open toolbar popup UI and then adjust the color settings. There are a variety of options available to choose from. From document body's "background-color" to "font-color", "header-color" and etc. Moreover, you can adjust the opacity for all HTML elements.
All the settings in toolbar popup are auto saved to the memory. There is also a (+/-) button with you can use to whitelist desired domain(s) from dark mode. Please note that, at the current version of the add-on, there is no option to see the whitelist table. You can only add or remove websites from toolbar popup UI. In order to turn the add-on ON/OFF, you can use the big "torch" button at the top center in popup.
If you found a bug to report, or have a feature request, please fill the bug report form in the add-on's homepage (http://mybrowseraddon.com/custom-dark-mode.html).