>It was such an effort that we only managed to get tests working for the registration and login flow, and only on Firefox ESR. They are frequent broken by chang

>It was such an effort that we only managed to get tests working for the registration and login flow, and only on Firefox ESR. They are frequent broken by changing CSS classes or IDs or the structure of the HTML. It sounds like you were approaching the end-to-end tests as an add-on and not part of your production code. If your problem is changing selectors, you need to make sure your developers know that changing selectors is going to make the tests fail and you need to equip them to handle it through tooling.