In the mobile version to scroll the menu?

Help please I can not understand what is wrong in the desktop version the menu works fine in the mobile version menu not to scroll, I thought that the problem with z-index like I tried to put nothing changes.
website: key.webraccoons.ru

Tell me what's wrong, thanks in advance
June 3rd 19 at 18:54
1 answer
June 3rd 19 at 18:56
$('.menu').on('click',function() {
$('body').toggleClass('fixed');
});

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