No Menu in Android or iOS

Hi – I’m using Pinboard 1.1.8 with a child theme. My site JessicaCys.com has a menu when viewed from a PC with a browser but the is NO MENU when I view my site on a mobile device. When I disable the child theme and use the parent; then I can see a menu. Where in the style.css would I see the code for mobile devices? Maybe the code is deleted on my child theme? Any help would be appreciated. Thanks