(<p>Try heading <a href="/">Home</a> to see if you can find what you’re looking for, or make a U-turn with your browser’s Back button.</p>). The "display:none" is to keep it out of site unless the page requested doesn't load for some reason.
Nothing to do with a menu. Eric has links to 2 menu stylesheets (quickmenu and superfish). Do you have those files? Ah, finally... Eric's online (he so seldom not here

I'm sure he can get you going in the right direction

https://www.callendales.com