Menus not working on mobile

[stpaultim]

I was working on this issue without creating an issue. I've already committed a PR to fix it, but realized that I should have done this in a more transparent way to get feedback from other users.

To demonstrate the problem, I created a simple fresh Backdrop CMS site using the latest release of Opera and added a few menu items. First without drop down menus and then with them.

This is how the same site looks with Basis

[stpaultim]

@olafgrabienski - I noticed that Opera did not have the same code for mobile menus as what is used by Basis. I believe that for things like mobile menus, I had intended to simply use the CSS from Basis.

The PR I merged, just adds CSS from Basis to fix this problem.

It worked for me on one site, but I have not yet tested it on others. I plan to test it on other sites, before issuing a release.

I welcome others to test and provide feedback. I'm happy to revert this if this is not the right solution or to swap in a better solution.