Just add a sibling element with
data-target to reduce one or more navs to a hamburger menu () on smaller screens.
.nav .sidebar to a block level element for a vertical navigation menu.
.popup for popup menus, rather than the default accordion style.
.popup.auto-accordian for popup menus on larger screens, which become accordion style on smaller screen.
.right to the <nav class="nav sidebar"> element for arrows on the left. In this demo, we use
float:right to position the nav, but this is arbitary, as it is up to you to position the nav appropriately to your needs.