I use a local homemade written html file as a start/homepage [HP]. Each time I open the browser my HP appears but it isn't in any container. Make it so everything is in a container, including locally stored content.
It's a Firefox API limitation which prevents automatically isolating file:// URLs, nothing I can do about it. (See: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/create)
