BEM naming, mobile-first, pseudo-elements

Hey, good work on this one. The layout is good and it resizes well when going in mobile.

Regarding your query, well I think you don't need to use z-index in here. But since you used it, the mobile state share button can't be unclicked right? Well that is because the footer overlay, the pop out one, it overlaps the share button. But since there is a z-index on your share button, you can just remove the z-index in your .footer and your footer-overlay selector.

This way, the pop up will not overlap the share button, it will be visible even when a user clicks on it in mobile view. Because the higher the z-index, the more it is prioritized right, so it hides them. But remove those that I mentioned, and the share button will appear ^^

@Krista Calleja, Great job on responiveness, regarding the share icon on the mobile view I sugesst that you include the share icon in the class="footer__social-icons-overlay" and use some sort of modifier or a extra class plus some js to get the behavior.