Please use the above css because if you look your site in Firefox, then you can see the actual issue. And regarding the menu issue we are little bit confused, so could you please explain more about the issue. If you want the menu same as desktop in the mobile version, then you need to edit the core file of the theme which take lot of time or you can concern to the developer or you can purchase the customization package, then if you face any problem, then please let us know.
Thanks for your patience! I’ll try to explain more clearly:
At the moment, your theme seems to switch from the “regular” to the “mobile (collapsed)” header menu style if the width of the browser window (or the screen width on a phone/tablet) is 1024 pixels (points on retina devices) or less.
I would prefer for this switch to occur only at 740 pixels (points on retina devices), so that the “regular” menu is still shown on ipads or on browsers in smaller windows, and that the “mobile” menu only shows on smartphone screens.