Primary Menu disappears on mobile devices

I am using Catch Base Pro and I am using a child theme. The primary menu is in the Main Menu position. The menu is no longer visible on mobile devices (or when reducing the browser window width). I'm guessing it happened when I updated the Catch Base Pro theme and has something to do with custom styles that I created in my child theme but I don't have any idea where to look. My site URL is www.coloradocaninerescue.org.