Store Style on local machine, not on / with the user account
I'm using the forum from my desktop and my phone.
On the phone I use the Mobil-Style, on my PC classic.
On both machines I use the same account.
If I have used my phone-browser and come back to my desktop, it uses the Mobil-Style instead of classic.
Using a different User on the phone is not the way because then I wouldn't get PMs.
So, I think, the used style should be stored on the individual device that is used