Disappearing sub-menus

I was doing some work on the site, nothing site-wide as I recall, but something I did killed the sub-menu display. My site is https://www.brewcitychurch.org, and when you hover over the menu at the top, then try to move down to the sub-menu, it goes away! I didn’t change any CSS or anything, which I assume controls that stuff. Anybody have a thought? It is using the “Clean” theme.