submenu doesnt slide into another menu

I have a problem. I selected ,,kończyna górna” and ,,kończyna dolna” under parent menu ,,schorzenia”. I also put some pages under each of that submenu but it doesn’t work. I can click it the submenu but it doesn’t open into another submenus(although it is selected properly in admin mode.

The page is http://www.mamtermin.pl

I hope you can help me.

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