Try (and fail) to do scaffolding with flexbox
Cut down on unnecessary nesting
Rename _navigation to _scaffolding; change folders
Grid CSS from 12-column -> major/minor/full/half

Instead of 12 equal-size columns, limiting the choices: full size,
half, major (~70%), minor (~30%). Because this is much fewer CSS
classes per breakpoint, at the time of writing this reduces the main
css size by 8% (17.1K minified to 15.9k) and the enhanced css by 29%
(17.2K minified to 12.2K) (!!!). Related to work for issue #5
First pass at a sample news post

For issue #5
- Add "Sample Pages" to main navigation
- (Fake) content and metadata for a sample news page
- Modify .card and groups of .cards with slightly different border
colors and spacing
- Change link underlines to gradient style
- Add sequence module (prev/next) styling
- Tag module styling
- Modifications to .media/.flag to allow for Sequences
- Add prev/next SVG icons