Just for everyone’s information, I was having some of the symptoms mentioned above (margin and such), but I was also having a LOT of Javascript errors.
As our Half-Elf Support Rogue mentioned, YOUR THEME ABSOLUTELY HAS TO HAVE wp_head() and wp_footer(), or you will get admin bar, margin, and javascript errors everywhere.
I downloaded a cheap theme which didn’t properly do this. When I added my head and foot, all was good!
The “display admin bar” settings don’t really matter, as they will function correctly with a correct head and foot.
