Update navbar design and improve search UI (#1084)

Co-authored-by: Gina Peter Banyard <girgias@php.net>
Co-authored-by: Sergey Panteleev <sergey@php.net>

Add visual regression tests (#994)

Co-authored-by: Roman Pronskiy <roman@pronskiy.com>
Co-authored-by: Derick Rethans <derick@php.net>