Set content width to 1200px

This expands the content width so that it matches the maximum width of
the content column in large viewports. This maximum width is only used
for Image and Gallery posts but is, still, the max.
Updating spacing for menu items in large viewports

This fixes an issue where the second row of items would be cut off and
obscured by too much padding.
Add theme template for post format archives

This allows for a custom page title on /type/format/ pages as well as
providing more flexibility with layout choices. Props to TwentyThirteen.
Update classes used on archive templates

archive-header and archive-title are more descriptive than the generic
"page"
Update CSS to use the new classes for archive titles