The design is broken, on desktop below a certain width the menu disappears, and there is no hamburger menu either so once you're in a section you're stuck. Also the links are not links, you don't know where they are going and the url does not get updated which makes it impossible to have incoming links other than to the root of the site. It also behaves unusually, if you drag a link it just behaves as a click.

Honestly if I came across this site in the wild I'd quickly pass to something else.