How do you make images stack on top of each other for full view of all, when using media query for small screens?

On the 13th item of this project, when the media query was applied for small screens, the images became stacked on top of each other, making it possible for all the images to be viewed as you scroll down the page without the need for horizontal scroll bars.
How is this made possible?

I used flexbox, maybe it’s not the way it was meant to be solved but works fine :slight_smile: