blurred #content instead of #container-main

Since I updated the responsive layout to have a main column and a
sidebar column, the menu script had to be updated to blur all content
rather than the just the main sidebar.
improved dual column layout

I added a true sidebar so elements on the right will float
independently of elements on the left. Changed .left to .post as we
transition to the sidebar layout. Also made some minor margin
improvements and removed unused selectors. Gave #overlay a z-index of 1
so the #content blurring will not glow distractingly. Major update but
will still require some tweaks that I can add soon.
renamed and reordered classes

I renamed the .left class to .post and reordered some of the elements
using it. Also cleaned out some old comments that are not needed
anymore.