Use best dark theme for Chrome, Windows 10, PC, Desktop, Mac, Chromebook
First, we'll show you how to enable dark mode in Google Chrome or Mozilla Firefox using an extension called Dark Theme for YouTube. This is by far the easiest way, but does require installing third-party software. If you want to avoid this (for now), skip down to Method 2 below.
Open up your browser (Chrome or Firefox) and head to the Dark Theme or YouTube page in the Chrome Web Store. Click "Add to Chrome" (or "Add to Firefox") button and then click "Add Extension" when prompted.
Once installed, click the extension button at the top right corner of your browser window (see screenshot below). Then go to Settings > Interface > Themes and select "Dark." Then click Save Changes at the
Chrome extensions are only available for the desktop versions of the Chrome browser and are not available on mobile browsers (i.e. phones and tablets). To install a Chrome extension all you have to do is visit the extension page and click on the "Add to Chrome" button.
If you want to install an extension on the new Microsoft Edge browser, read our guide on installing Chrome extensions in Edge: How to Install Google Chrome Extensions in Microsoft Edge