Horizontal Responsive Menu with submenu into vertical

Question

I use since severals years a simple horizontal css menu with submenu. I try to modify it to tranform in responsive.

Answer 1

Finally I change my basic horizontal Menu. And it's give that

    
Home
    

        Réalisations
        

            Link 1
            Link 2
            Link 3
        
    
    
Contact
    

        

            

            

            

        
    

And it's good. I let you my code to help you :-)