Comment by sorcercode

Might I also suggest the Firefox addon "Container Traffic Control" - A Firefox addon I built to make it even easier to use Containers

https://addons.mozilla.org/en-US/firefox/addon/ctc/

When you start to use Containers (feature the Author of the article talks about), you'll start to want a little more control in how the containers open especially for sites that you allow on more than one container

Source came be found here: https://github.com/kaushikgopal/ff-container-traffic-control