If you’re running Google Chrome 57 or above, it turns out there’s a hidden dark mode. Reddit user _paul- found the menu, which you can enable with a quick jump into the console menu.
The dark is, as you’d expect, dark, with a black background and white text. Here’s how to turn it on:
Open up the developer menu by pressing Ctrl+Shift+I on Windows (Option +Command+I on Mac).
Click on Console.
Paste in this line of text:
document.cookie=”VISITOR_INFO1_LIVE=fPQ4jCL6EiE”then tap Enter (note: for the time being, head over to reddit and paste the code from there, as we’re having some technical difficulties).Close the developer window and refresh the page.
If you’re logged into your YouTube account, click the profile icon on YouTube. Then click on Dark Mode. If you’re not logged in, click the three-dot icon that appears, then select Dark Mode.
That’s it, you now have an experimental dark mode available to you. Commenters are suggesting it works in other browsers as well. Firefox requires that you delete old cookies first, and it should work on Edge out of the box. I couldn’t get it to load in Safari though.