This page shows Bootstrap menus with Smartmenus CSS applied. Note: the menu in the navbar was specified as a Bootstrap menu and this seems to have converted its third-level items to second level (under "Community", in the original menu construction there are two second-level items, "Groups" and "Teams", and each of these has children, but it doesn't show up this way in the final menu).

Below is navbar HTML from: http://vadikom.github.io/smartmenus/src/demo/bootstrap-4-navbar.html, which uses Bootstrap menu construction and has multiple levels and opens on hover.

Visit the page in a mobile device or use a responsive emulator to see small-screen appearance and behavior.