Navigation Dropdown menu is cut off when not in full screen

The navigation menu for our services tab is cut off when not in full screen mode. Is there a code we can use to make the drop down two columns or scrollable? 

@kristicchilton Hi! Can you share your site URL for context? 

You can use this code to Website Tools > Custom CSS to create scroll bar

div.header-nav-folder-content {
    max-height: 400px;
    overflow-y: scroll;
}

Or this CSS code if you want to make 2 columns

div.header-nav-folder-content {
    column-count: 2;
}