I am making my first responsive webpage. It's desktop-first, and since it's a simple one-column page I need only one media query, for mobiles. I have a different nav bar for the desktop from the mobile. So I put both navs in the HTML. I set the nav that is for the mobile to "display:none" in the main part of the css, which makes it disappear from the desktop version. I set the desktop's nav to "display:none" in the query, which makes that nav disappear from the mobile.
The trouble is that I can't make the mobile's nav visible again in the mobile version. How do I undo "display:none" in the mobile query?
(The page is http://www.birdwatching.com/optics/2018_Kowa_scope/kowa-tsn-553-review.html)