Why doesn't vertical scrolling work in mobile browsers?

Question

css

Guys, I'm making a mobile version of the site on bootstrap3
For a menu that leaves on the right, I use this jasny.github.io/bootstrap/javascript/#offcanvas-ex...
The problem is that the menu is long and there is no vertical scrolling in mobile browsers - as if set overflow-y: hidden. When testing from the desktop, vertical scrolling appears.
Menu example jasny.github.io/bootstrap/examples/navmenu
When you click on Dropdown, the submenu expands, but the scrollbar does not appear, the menu does not scroll down. Please tell me how to fix this.

Answer 1

By default body is added overflow:hidden when opened. Try adding the data-disable-scrolling="false" attribute to the menu. Solution from here