[Theofrastus]

Looks great! Useful for privacy but also to keep work and private life separated. Will be on the lookout for other OS versions!

[tgv]

Firefox offers multiple ways to do that: you can use containers or launch different profiles from about:profiles. The latter has no way of telling the windows apart, unfortunately. This tool seems quite handy, though.

[crtasm]

Setting a different visual theme for each Firefox profile works well for me.