Ease jank by popping fixed elements to new layers

Fixed elements which are not on their own layer often cause whole-viewport repaints with every pixel scrolled.
Removing jank caused by fixed elements

For 2x view
Merge branch 'patch-1' of https://github.com/brianblakely/Demo-for-National-Geographic-Forest-Giant into brianblakely-patch-1
move css changes to sass