menu on iPad

Hello, I looked at the website Laura.hagmeijer.nl on the iPad. After clicking on the hamburger menu I not only saw the menu, but the also the content of the shopping cart. And after the shopping cart content the header occur. Next step was looking at the MacBook. After making the website smaller (mobile format) the same thing occurred. Is this a bug or can I do something to prevent this. Kind regards Hans Hagmeijer