Okay, it's getting there. My content is no longer underneath my sidebar, and that's a big improvement. However, the top-level tabs (but not the sub-menus) are now overlapping the main content.
A picture is worth a thousand words, so see screenshot here.
This is not a dire dealbreaker, but it's still annoying and unsightly, especially on the post/page writing pages. If the sub-menu items can fit nicely, surely the same thing can be done to the top-level ones.
On the bright side, all the other content-fitting issues seem to have been addressed. Almost there.