When a page is scrolled, the top nav menu become fixed. Depending on the page content this caused issue where focused links or buttons may be hidden behind the nav menu.
Props afercia, davidakennedy, Fencer04
Fixes#38476
Built from https://develop.svn.wordpress.org/trunk@39225
git-svn-id: http://core.svn.wordpress.org/trunk@39165 1a063a9b-81f0-0310-95a4-ce76da25c4cd
* Relies on header skip link instead of l10n variables in JavaScript.
* Fixes issue where scroll down arrow appeared next to the navigation on the front page with no header image or video. It now only appears with a big header.
Props enodekciw, laurelfulford.
Fixes#38502.
Built from https://develop.svn.wordpress.org/trunk@39073
git-svn-id: http://core.svn.wordpress.org/trunk@39015 1a063a9b-81f0-0310-95a4-ce76da25c4cd