How do I make a dropdown menu open and close on a Windows touchscreen in Edge and IE using CSS

I am working on a responsive version of our website and discovered in testing that our dropdown CSS navigation doesn't work in Microsoft Edge and Microsoft Explorer on a Windows touchscreen (I am testing on a Surface with Windows 10). The navigation works fine using Firefox, Chrome, and Opera. I have searched online for more information about this, but have not found much about this problem, so I don't know if this is a known issue or if the problem is in my code. Has anyone found a solution for this? I am trying to do the navigation with CSS and am using aria-haspopup="true". The page I am working with is http://wgm.org/r-home.