Reply To: How can a button be placed on top of an image?age?

[JeroenR]

You can try something like this: https://codepen.io/jeroenreijs/pen/JjjpZOg.
The popup has absolute positioning. The DIV with class .thumbnail. Because the other button is a child of the DIV with class .gallery-item, I added position: relative to that class as well.
Now you can maybe play around with the positioning as they are now both in the center and therefore on top of eachother.