The forum menu bar in Safari looks different from Firefox. (Same username, same time). Some extra buttons are in Safari, like "Mark Forum Read". See attached screenshots
I believe the menu options are JS-driven but the key factor is that the browser reveals to the server that it's second-class in nature and will not support the scripting - and thus is delivered a different page.
Firefox plugin: NoScript will let you simulate this too
I'm using safari but i don't have 'marks forum reads' on the menu bar and also the donate buttoon only shows up when i am viewing a thread its not there when i am in the front/home page of EF