twentyfifteen_post_nav_background() – Add featured image as background image to post navigation elements.
twentynineteen_add_ellipses_to_nav() – Add an extra menu to our nav for our priority+ navigation to use
twentynineteen_add_mobile_parent_nav_menu_items() – Create a nav menu item to be displayed on mobile to navigate from submenu back to the parent.
twentytwenty_add_classic_editor_non_latin_styles() – Output non-latin font styles in the classic editor.
