It's pretty simple; I'm just too much of novice to quite make it work.
If a user is logged in, I want the nav pushed further to the right. If they are not logged in, I want the nav pushed not quite as far to the right. Why I want this is complicated, and tiring. It has to do with my login modal, and hooking it to the nav (via the branding and absolute positioning), and resizing the nav section so it wouldn't block the modal's link, etc. etc., and with the fact that when the user is logged in the login button goes away, so I want the nav pushed further to end where it did when the (fake) login nav item was there. Anyway, here's the crappy version of what I want to put in functions.php: