For anyone who stumbles on this:
After much (painful) searching through Webkit documentation, improper SubPixel handling is a well documented bug and needs to be fixed to make these types of issues go away permanently. The only sure work-around I can find is a negative pixel margin fix. This qusetion goes into some good detail on the matter.
In regards to my particular issue with seven columns, a negative pixel on each of the seven columns was creating a margin on the right-hand side of the screen. What fixed me was the idea of only applying the negative margins to every other column. So now columns 0, 2, 4, and 6 all have a margin-left: -1px
and the other three do not. It works for now, let's hope they get to addressing this issue sooner rather than later.
Cheers.