Mobile nav shows not correctly

in CSS (panel or style.css of child theme):

@media (max-width: 979px) {
	.navbar .nav > li {display: block !important}
}

or you could wrap the lines from 20 to 52 in your child theme’s style.css in a @media condition:

@media (min-width: 980px) { // line 19

} // line 52