1-2-3 to 1-2-4 index grid pattern (shift for large breakpoints)
and other fixes for padding and typographic balance
scaling of excerpt index items increases for large screens
new archive link design
visual fixes for archive links
move back-to-top item into footer component
Merge pull request #83 from opattison/new-grid

New 1-2-4 grid - resolves #82 #84