Style .lt-ie10 Browse Happy message for browsers older than IE10 in _header.scss and _includes/header.html.
Add dark gray to black horizontal gradient to the secondary content area, as well as make text white.
Apply -webkit-tap-highlight-color to only form elements in _base.scss.
Reduce amount of $yellow to 3% to mix into the $white through $black _variables.scss.
Add :hover and :focus states to the main navigation buttons and add white gradient over top 300px of body.