Hi Leo
the Optimizepress support sent me this CSS.
@media only screen and (max-width: 767px) and (min-width: 300px){
#mobile-header.toggled .main-nav > ul, #mobile-header .menu-toggle, #mobile-header .mobile-bar-items {
display: flex;
width: 120px;
margin-top: 20px;
}
.menu-toggle .mobile-menu {
padding-left: 10px;
margin-top: -20px;
}
}
The mobile menu is now clearly visible.
Thank you so much for your help.
Paolo