GitHub Night Mode

You don't necessarily have to be a developer to know just how much strain can be put on your eyes when working long hours in front of a computer.
In situations such as these, even the tiniest of details end up having a very significant impact on your concentration levels and, ultimately, your productivity. That's why, for example, most IDEs come equipped with so-called dark themes or night modes.

Brings a useful Night Mode to GitHub, only in Chrome

Unfortunately, GitHub's repertoire of features does not offer much regarding customization, hence, there's no way of selecting more suitable colors for dark or poorly lit work environments. However, there is a way of experiencing GitHub in "Night Theme, " and it comes in the form of a browser extension for Chrome, generically-dubbed GitHub Night Mode.
First and foremost, you should know that this extension is not (yet) available in the Chrome Web Store. This means that you will have to manually install it, but, fret not, it's not as difficult as you might think.

Not your typical installation process, but not at all challenging

Start off by downloading the package from our servers or the provided official link and extract the contents using your computer's default archiving utility. Next, head over to Chrome's Extensions section (either type in "chrome://extensions" in the address bar or access it the typical way from Chrome's main menu) and make sure you drag and drop the unpackaged folder (github-night-mode-master) onto Chrome's main window.
The extension should also make its presence known by integrating with Chrome's toolbar, but you might as well hide its icon altogether since there's no real way of interacting with it. From this point onwards, GitHub's UI should be presented in a typical dark-grey-themed mode,  without requiring any type of intervention on your part.

Chrome extension that makes GitHub a lot friendlier on the eyes of those working in dark environments

With all that in mind, GitHub Night Mode is a stripped-down, no-frills Chrome extension that does its unique job rather well. In theory, at least, there's really not much we can reproach this tiny useful Chrome extension apart from, maybe, the fact that it not yet listed in the Chrome Web Store, from which it would have been a lot more accessible.