Hi!
We’ll have an update soon to fix this issue. It seems that when you don’t have submenus the float:right of the menu affects the mobile menu too. So to fix this, just go to responsive.css on line 1446, and 468, and add to nav > ul the following:
float: none;
margin-left: 20px;
margin is added to offset the menu from the left a bit, you can change it if you like :)
Hope this helps