macOS has a dark theme and this dark theme doesn’t just change how the menu bar, the dock, and the context menus look. It also changes the stock apps and gives them a dark UI to match. Unfortunately, sometimes the apps don’t respond to the theme change. You get light theme apps with dark theme. Here’s how to fix it.
This may be a long shot but it’s worth trying just the same; toggle the themes. Quit all the apps that you have open and then switch to the light theme. Switch back to the dark theme, and then open the apps. If they haven’t switched to the dark theme, move to the next fix.
Quit all the apps that you have open. Open the Terminal. You can search for it in Spotlight or open it from Launchpad. Enter the following two commands, one by one.
defaults write -g NSRequiresAquaSystemAppearance -bool No
You also need to kill Finder. The easiest way to do it is to open Finder, click the Apple menu, and hold down the Shift key while doing so. You will see a Kill Finder option in the menu. Click it to kill Finder.
After everything is done, open the stock apps and this time, they will have switched to the dark theme. If it doesn’t work, log out and then log back in. Killing the Dock should do the trick so logging out is necessary only if it doesn’t execute the change.
In the event that you like this random bug i.e., you’d like to get a dark menu bar, a dark dock, and dark menus, but keep everything light, you can run the following command in the Terminal and replicate it.
defaults write -g NSRequiresAquaSystemAppearance -bool Yes
You will need to either kill the dock or log out and log back in for the change to be applied.
After executing the command to fix this bug, you should be able to switch between the themes and the apps will reflect the change. If the apps don’t change their theme immediately, quit them and then run them again.
The bug shouldn’t occur repeatedly after you fix it but it can happen even if you’ve created a brand new user profile, or if you’ve just updated to the latest version of macOS.
Third party apps will reflect the dark theme only if they’ve added support for it. Chrome just did, so make sure you update it to the latest version.