I did the migration on Blocs3, but just realized that the burger is not here anymore for small devices. (I also lost an icon which reveals a hidden bloc).
I try to get how to get back a burger without the need of redo the nav bar.
Here is the website afther the migration 
http://phl.website
Thanks for your help.
I found out that the burger was just on light mode and should be on dark mode.
It was here. I just couldn’t see it.
I should have checked longer 
Try setting the navigation theme.
https://help.blocsapp.com/knowledge-base/change-toggle-navigation-symbol-colour/
Yes, I figured it out.
Thanks for you help.
Now, I try to find where is the icon I put around there to reveal a hidden bloc 