Joomla Website Main Menu Submenus need scroll arrows for scrolling submenus

We need customization on our joomla website Main Menu on big screen size view like Desktop & Laptop View Sizes as we have plenty of sub menus & sub menus of sub menus. I want some customization in the main menu on Desktop/Laptop View, if a menu has so many child menu which exceeding page view size then some scroll should add automatically to it. Please take a look at [login to view URL] --> Courses-->SAP--> Sub Menus. Please scroll to those sub menus you will see the scroll up & down arrows on menu. We need similar customization on our joomla website main menu.