`MindShield` injects a style sheet and javascript content script on YouTube, Facebook, Twitter, Linkedin, Instagram, and Google Search when you visit them in the Safari browser on Mac, iPhone or iPad. This allows you to hide distracting elements and see them when you want.
After you have installed this app, the extension will appear in Safari > Preferences... > Extensions . Here, you can turn the extension off and on - or uninstall it.
If you have any problems, contact me at ulrik.lyngs@gmail.com or create a GitHub issue on the repository github.com/ulyngs/mindshield-open-source.