Firefox App (iPhone/Android) Submenu doesn´t open

Hello,

sorry for my bad English. I created a website with a horizontal menu, everything works on my Safari, Firefox and Chrome.
But when you are in Firefox on the iPhone and you will tap the menu (1st Level) for getting the submenu, then the reload bar starts and the page will be loaded. You will see a few seconds the submenu and then it is away. It feels like does the one touch function not open the submenu, rather the page behind the (1st level)

the website is:
www.vollepatrone.de/joomla/

maybe you can help me?

Thank you

Hi
this is more something due to the multiple browsers behavior
you could go in the responsive options and switch your menu to be with the hamburger icon on mobile
CEd