@Bill, in reply to a PM:

Create a wide box for the HTML Code - put that into the Placeholder Body. Set the Placeholder to be Repeat on all pages. It needs to be deep enough to handle the showing of the tallest submenu.
The CSS Code goes into Website > Head.
The JavaScript Code goes into Website > Body.

As the code uses an id for 'menu' and 'responsive-menu', you need to check the codes generated work in a Variant. I have been lucky so far or perhaps Xara has sneaked in a fix after so many years.

Default RM in a Web Block design: CSS+JS - Responsive Menu.xar. The JS is probably optional.

Acorn