problems with site in IE11

Dear,

I'm creating a website with the Rooms template.
In my main menu on the left of the website there are menu items that do not show up when used with IE11 on smaller screens (for example on a 19" monitor).

On my 19" monitor I don't see anything under vacatures and when I scroll, it only scrolls in the right side of the site but my menu does not scroll.
Also when I resize my window in IE11 menu items dissapear and cannot be reached by scrolling.

You can see my website here: www.laptop-onderdelen.be

Hi there, I could not see any issue with IE11, see video attached