Adding main site nav card to post page

Moving much of the index page styles into the site-wide css file, as
well as making top of large full-post card scale better for long titles.
Adding recent posts card to post page
Miscellaneous style fixes

- on home page make entire featured card block a link
- fixed text align bug on header of featured card
- made "Recent Posts" text white, capitalized
- added margin to bottom of page
- read more text looks a little better