Trying to replicate a site setup I came across, getting stuck.

Site URL: http://www.observationkit.com

Sorry it's a little long, trying to give info. 

I am trying to replicate the site setup I found here: observationkit.com – I want to have a grid of items, where you can click each and open a lightbox with an image and text (that can scroll and doesn't cut off). The hover effect that shows titles would be nice, but is less essential. I'm decently familiar with web design but less familiar with Squarespace, and I cannot figure out how they got it to work. 

Observation Kit uses the Universal Filter plugin, which is where I came across it – OK's one of their example sites. I've gotten the filter part working fine. 

What has gotten me the closest to what I want on the pop-ups is using Summary Blocks linked to Store items – this gets everything nearly correct, EXCEPT that there is a character limit to the product excerpt in the pop-up... and so I can't get the full copy to display, unlike how the pop-ups on Observation Kit have extra long copy that scrolls.

For my other options, Summary Blocks with Blogs have no pop-up built into them, and Summary Blocks with Event Pages I haven't tried (but it doesn't make sense that they'd work). I've also done some forum searching, and it looks like people have said in the past that the product excerpts on the Store pop-ups can't be made longer – so I assume there must be some other way to go about it.

I'm worried that the issue is I'm on 7.1 – I see that while on 7.0 Summary Blocks used to support Gallery and Project Pages, now they no longer do. So it's possible OK's site is using one of those to make it work... but I just don't know. 

Anyone have any clues how I can get the effect I want? I really appreciate the help.