Windows 7 supports dark mode, which can be activated by going to Settings and selecting Dark Mode. To install a black theme, you need to go to Control Panel > User Accounts > Change User Account Settings > Never Notify, and then run Team Resource Changer and Universal Theme Patcher. There is a bug in the "Stretch" wallpaper option that causes a black wallpaper. To avoid this, you can select an alternative option like "Fill," "Fit," "Tile," or "Center". ^{howtogeek.com 3 1 2}