When I click on the hamburger icon on my mobile website (powayelitedental.com) on iphone via chrome or safari, the navigation appears cut off with only half of the word "home" visible. 

I am using the purple haze standard theme. I had tried various other standard themes which all have caused problems with navigation disappearing on desktop/ipad/mobile. This is the first theme that has a functional navigation on desktop/ipad, but the mobile version is just not working for me. What can I do to fix this issue?