Next update has warnings about bus contention (multiple things into one node) when its an issue, and will have a proper show solution button.

For level 1.1 the solution is basically to take the ground and use that as a singular input to the source pin of an nmos transistor, let the input to the level be the gate pin of that same nmos transistor, and to let the drain (top) pin of that nmos transistor connect to the level's output