Menu items do not scroll

Hi
This is a beautiful theme and I love how professional it looks. My one concern is that the menu is not scrolling on smaller monitors. Here is a picture:

https://unhoop.ph/wp-content/uploads/2016/03/Capture.png

There is a lot of menu items and at one point it will not scroll down to show the other options. is there a way to fix this or to give the UL a scrolling option? Thank you in advance ??