On mobile all submenus open in NavBar

[GiraffeCoding]

When the website is loaded on a mobile device (ie anything lower that 768px width). The submenus within a navbar are always open when the parent dropdown is opened.

It add the display:block element to each submenu dropdown-menu.

However when you load a browser window above 768px and then resize to a mobile device the menu then works.

Any ideas?