When booking a service online that has a required number of add-ons it's easy to overlook the greyed out "Choose at least 1" and if you don't add an option, when you go to add the service nothing happens. There's no alert to let the client know why they're unable to add the service. If a client were to mark an add-on and then unmark, it turns red to alert them they must choose one. Would be great if that happened when they click "Add" so they know why the process isn't moving forward