For those who read documentation a lot. It is implemented using user style and the colors are same as in the dark theme from Microsoft Visual Studio 2013.
Screenshots: tkirill.org/msdn-library-dark-theme#screenshots
- Install Stylish extension bringing user styles into browser.
- Visit our page on userstyles.org: userstyles.org/styles/109048/msdn-library-dark-theme.
- Press "Install with Stylish" button.
- For update go to
Stylish -> Manage styles
then right click on style and click "Find updates".
Same as Firefox. Stylish for Chrome: chrome.google.com/webstore/detail/stylish/fjnbnpbmkenffdnngjfgmeleoegfcffe