Clicking "add to cart" just shows me "cart empty"

[Sniegu]

Hi,

If you go to https://headbanger.pl/shop/cds.html and click Add to Cart, you will see that the next screen only shows "Cart empty". Tried changing the template, it shows the issue there too and I can't see any JS errors in the console. Thanks in advance.

[jenkinhill]

Versions?  http://forum.virtuemart.net/index.php?topic=79799.0

+/- product buttons don't work either.

Console shows errors :
ReferenceError: jQuery is not defined
Error: UIkit requires jQuery
plus several mixed active content errors.