- Flexbox responsive behavior fixed with specific .col-{breakpoint} classes now added
- Dropped the make-col mixin in favor of a column-basics placeholder that we can extend across our grid infrastructure
- Updated docs to use required .col-xs-12 (as a safeguard for when folks enable flexbox mode--this isn't necessary in default grid mode)
- Update flexbox grid docs to include responsive docs, tweak some other bits too

flip things around again, no more base class, try out some new stuff to keep responsive flex grid working

[skip sauce]

- Simpler main nav on all pages
- Back to purple masthead on homepage instead of dark graphite
- Active link styles on the main nav
- Cleaned up sidebar nav
- New docs layout name
- Homepage copy edits
- Updated bright purple docs color

Add tabindex="-1" to main #content to work around bug in Chrome (and old
WebKits) and IE
Update advice in accessibility section
Include patch in docs CSS to suppress outline when #content is focused
(particularly as Chrome sets focus as result of mouse click for
tabindex="-1" elements)

Additional markup for the skip link (to ensure it has the same effective
width as the main content, and to provide an outline around just the
link text) plus some basic styles...make it look a bit more in keeping
with the overall look and feel of the docs.