Menu disappear

Hi! I updated Enfold on a client site and the code change because the menu now disappear between 1200 px and 768 px. Because the menu is long, I want to have the burger menu under 1200px. Here the code I’m trying to adjust, the main text menu disappear as I want it to, but I can’t find the code to make the burger menu appear:

@media only screen and (max-width: 1200px) and (min-width: 768px) {
ul#avia-menu.menu.av-main-nav {display: none!important;}
.av-hamburger-box {display: inline-block;}
}

Thanks for your help!