StudioKSR

The fact that it's 2024, this is possible with every other image on every other way in Squarespace, but not in Gallery? What possible reasoning/mindset of a developer was put into motion here? It's these simple, annoying aspects that makes the platform more and more unusable. It can be done. It's done in every other way. Why not with gallery images? And no one wants to use CSSS to do that? 

Hi @AtelierDeux. The reason you're seeing raw code displayed on your site is due to inserting the code in the wrong location.
I've updated the original post to include links that explain how to add the code. Note that you have to use both the CSS and the JavaScript together, and insert them both according to the directions. In your case, you're using per-page header code injection which may also work, but best to do as the directions say (and now link-to).