I can see that the problem is visible when the page width is between 964 and 948 pixels. For some reason my unordered lists are not stacking on top of each other.
You said that it might have something to do with the vertical scroll bar, if that is the case how would I compensate for that and make it work in all browsers.
I have moved my markup, css, and styles to codepen
For some reason jquery is not working.