Loading external post/content to a specific div (jquery)

Hi, I’ve been playing around with the grid-a-licious theme, and found some really cool sites similar to the theme:
https://home.visuaal.com/
https://spacecollective.org/projects/The-great-enhancement-debate

The question is: any idea on how the post contents were loaded similar to the sample above?

When the user clicks on each box, the specific div expands and displays/loads the entire post. When the close button is clicked, the box returns to its normal state.

I’ve been figuring out how to grab the content from the post’s permalink and place it in the box. I’ve also searched/experimented through a lot of jquery scripts but no success to make them work with wordpress

Thank you