rm page_margins
rm col1_content
combine element and div#element
rm col3_content (replace by sidebar)
rm content_wrapper (replace by main)
rm markup clearfixes
refactor footer
pep8
allow the navigation to break
replace instance header background by a scaling gradient
fix left/right padding
update print
layout in %
fix settings layout
fix instance header
fix instance nav
Merge pull request #682 from xi/feature-480-refactor-grid

refactor grid