Mobile Menu Not Accesible

For Make mobile menu accessible, You have to make parent menu as a Custom Link.
For create custom link you have to simply go to Dashboard -> Appearence -> Menu -> Custom Link
Add link Text & put '#' in Url, After add it in menu, Remove '#' from it.
See the following attachment for more details :-

https://i.imgur.com/bI9D1sl.png

https://i.imgur.com/IqVbRWj.png

Also go to your Theme Customizer -> Additional Css -> Paste the following code there

@media only screen and (max-width: 767px) and (min-width: 480px){
    .ul.dropdown-menu {
        float: none !important;
    }
}