Responsivity adjustments for login area

Hey, there, Atko. Long time no see. I was away for a few days, so I hope I didn't miss too much. :-)

Anyway, this commit basically does the same thing as my other responsivity commit, but I made it more responsive. The margins are cut off at around <950px and the shaded box is removed at around <870px. I do remember you talking about issues with your phone, so I hope this fixes it. If it doesn't, please let me know with a screenshot, if possible, and I'll get right on it.

As for the `Delete backup file that shouldn't have made it to previous commit`, you can ignore it, since the file in question was created in this pull request and deleted right after. Complete blame on WinMerge. :-D