How to hide folder items in mobile navigation (Wells template)?

Site URL: https://www.jordangraceowens.com

Hello! I have navigation links nested inside a folder, and I'm trying to hide them on mobile. They're hidden on desktop (until you click) but everything shows up on mobile. I've tried searching for custom CSS but haven't had luck with anything. Thanks for any help!

Add this to Design > Custom CSS

@media screen and (max-width:800px) {
li.mobile-folder ul {
    display: none;
}
}