Can't add a source URL as the value as a source

This might be a sib-core issue, or a CSS issue on our side, I do not know.

Some context beforehand

I'm thinking that for now, we should federate all instances with one another. In a couple of months, the end user will decide which sources they select in their application. For now, we're probably fragmenting the ecosystem by hiding some people from each other, as a time when we don't have enough Job offers, Users, Circles for the numbers to be a problem for the end user.

The problem

What I would like to do is to be able to plug an instance sources on another instance's sources, for example:

This works, but the UI is a mess then: