MAJOR CHANGE

[#67873516] Navbar now contains primary search form. It expands
on-click via javascript.
Remove search bar from actions

[#67873516] search bar removed from user actions. will remain in user
actions for search results for now.
MAJOR CHANGE

[#67501316] Layout changes to welcome/feature banner. Form and button
styles stripped—WIP to continue in [#67653700]