Minimum Width, Larger Hit Size on Sidebar Splitter

This PR addresses a couple usability annoyances I found.
1st, this sets a minimum width so users can't collapse the sidebar into an unhittable, unresizable, 0px unspace. I used 40px which keeps the favicon still visible.
2nd, added a 3px invisible hit region to the sidebar splitter so it's easier to grab. Stolen gratuitously from our devtools sidebar css.

Did some minor cleanup of osx.css. Restored vvuk to the Creator of this addon, changed the id to be reflective of what it is (and not who), and bumped the version number ever-so-slightly indicating it's forked, updated and much-improved status.

Please accept me! <3