I am not sure the below issue is what you mean, but @weaver, this is what I observe.
As you load the page, the menu items occupy a certain width. As soon as you hover on a menu item, the width expands a bit and stays expanded after you un hover. If you do that on every menu item, it will expand a bit more every time, Once you have hovered all of them the menu bar items now occupy a wider area.
Will keep looking, but have not figured it out yet