I've been playing around with supporting 'Dark Mode' in this site ever since it was introduced in macOS. If nothing else, it's a fantastic way to showcase photos. With its introduction on iOS last year, I finally bit the bullet and added full support.
Debugging Dark Mode can be troublesome though, as testing often necessitates toggling it on and off to check a design in both modes; something macOS (unlike iOS) doesn't provide a convenience for.
tell application "System Events" tell appearance preferences set dark mode to not dark mode end tell end tell
Their approach adds a Service to the Services Menu, and then describes how to get this to show up on the Touch Bar. It doesn't--in my opinion--go quite far enough though, as they don't add a global keyboard shortcut for moments when the Touch Bar is unavailable. You can do this by selecting 'Services' in the 'Keyboard' section of 'System Preferences', finding your new service, and recording the key combination you'd like to use:
Check out the original article for full instructions.