Adjust the CSS using javascript to create functionality I need

I need someone to use js to append css classes to my list elements. They are currently generated by a CMS, so I can't directly edit how they are written in the HTML file. 1. Here is the navigation with the correct CSS classes applied: [login to view URL] 2. Here is navigation with the navigation as the CMS creates it: [login to view URL] So I need you to write some simple JS that rewrites the classes on the <LI> elements to match the first example. Should be easy!