LJ has just removed the 'view in old style' option.
LJ likes to take a page style every week, put it up against a wall and shoot it-- so that you must view everything in mobile style or you must use new style or you must whatever.
LJ- breaking what didn't need fixing since far too long.
ETA- wait, what? It's under Display, not Presentation? Great! Tick it back! But then it's not under Display anymore. Guess it only appears when you're in new style.