You have three types of menus:
- Vertical left bar (like this website) .left-bar
- Top navbar
- Bottom navbar (only mobile/tablet) .bottom-mobile-bar
To switch menu layout we can't have easier, you just have to add .left-bar and/or .bottom-mobile-bar on .page-header.
HTML markup and JS are the same, It's just a few CSS rules which change.
<header class="page-header left-bar bottom-mobile-bar" role="banner">...</header>
Click here to see full HTML markup