Menu is not responsive to iPhone.

I am using News mix light theme for my website, and it is working just fine if you are on a computer. It looks good on iPhone and iPad, except for the menu layout.

In my menu i have: Home, Forum, Advertisement, Log in, Register.

But when you are surfing on an iPhone, or iPad, there are no of these above, it only says ‘Menu’, so there is really no good way to navigate on my website if you are surfing on a iPhone. And nothing happens if you click on it either. Hope you can understand what I am trying to say, and if you know how to solve this, it would mean a lot to me. Thanks!