Quote:Containers with Transitions is a brand new Firefox extension that improves the functionality of Mozilla's own Multi-Account Containers extension for Firefox.

Mozilla launched Containers as a Firefox Test Pilot project in 2017; the organization did not integrate Containers natively after the Test Pilot project ran its course but released the Multi-Account Containers extension instead. Firefox users who wanted to make use of Container functionality in the browser could install the extension to add support for it to the browser.

Third-party developers created specialized Container extensions, e.g. to restrict Facebook, Google, orYouTube to a container to limit tracking. Temporary Containers on the other hand creates self-deleting containers.

Containers with Transitions

Containers with Transitions is a fork of Mozilla's Multi-Account Containers extension that takes Mozilla's extension and improves it. The extension supports all features of Multi-Account Containers; you may use it to maintain a set of containers, and load sites into containers to separate their data from others.

What Containers with Transitions adds is the following: the ability to create rules to define in which container links are opened that are activated from specific domains that are open in containers.

Full reading: https://www.ghacks.net/2019/01/02/containers-with-transitions-makes-firefox-containers-more-useful/