jackiemcdean on "Mobile Menu Doesn't Work"

My mobile menu doesn't work since a few weeks. In the desktop version everything is fine, but on a smartphone the menu button appears, but nothing happens when pushing it. I tried to deactivate all plugins and installed an older version of WordPress, but nothing helped.

Can anybody help?
That's the site: http://tvhindelang.de

Menus are taken care of by the theme. What theme are you using?

Thanks for your reply. I used DynamiX theme.