Modality is ok. The reason being, a 'login' is often an interruption to the normal flow of experience. Trying to do 'A' then 'B' - need to login for 'B'. This i

Modality is ok. The reason being, a 'login' is often an interruption to the normal flow of experience. Trying to do 'A' then 'B' - need to login for 'B'. This is why modals exist. The background to the modal gives the context to 'where the login is happening'. If there is no context then it can have it's own screen. The absolute worst is when you're doing a bunch of stuff, you login, and the app does not forward you on to 'that thing' you were trying to do, rather, you just get to the home page after login and have to re-search etc..