Hey @recetteitalienne,
If you are adding other content to the same footer where the Instagram Feed currently is, it would not work. This is due to how the theme has set up this footer to have specific “areas” for widgets. What the above CSS did was ignore this, and take the whole space. This means there wouldn’t be space for other content in the same footer.
You may want to try using a separate page builder instead to create a section for the Instagram Feed. Then you can use the footer for other content in any way you like.
If you are unsure of how to use your theme, see if there is any support available from the theme creator as unfortunately, we can not provide specific support for all different kinds of feeds. If you do still have issues with our feed specifically, I would be happy to provide further assistance of course.
Best regards,