Make mobile menu have the nested menu items stay nested???

I love the shuttershot theme, and i was wondering if anyone knew how to make the items stay nested when it goes into mobile view? Currently, it expands them all out, but i am having issues with being able to scroll down and see the bottom menu items. It’s like it thinks it has reached the bottom because it keeps bouncing back up, but there are a couple more items that i am unable to click on.

I figured making the items nested would fix the problem since the menu would not be as long. If anyone knows how to fix it without nesting the items, i would be open to that too.

Website it kadinzim.com

Thanks!