Why does the menu open on the mobile version of a wordpress site?

Question

WordPress

I don’t remember what I did, but the menu stopped opening in the mobile version of the site.
The problem persists after updating the theme version.
website https://avitax.ru
Please help

Answer 1

Probably the problem is that the libraries and plugins are not included.
See the functions.php file, there may be an error (usually javascript and css are included in this file).