How to make grid items span two columns with CSS and JS in masonry?

I am using Edge theme. I love the masonry layout, but I don’t like that it shrinks all wide images into a single column.

I tried creating a css class for double wide items, but the theme isn’t that simple, because the masonry grid isn’t just CSS. There’s a javascript file that takes the CSS and packages it into the final layout.

On the Desandro site, there are instructions for responsive layouts, but I’m not totally sure where to inject what code.

I have a local version of my site running in Docker, so I can trial-and-error my way through this. So, even if you’re not 100% sure but you have some clue, feel free to suggest ideas!