Hey Dan,
Unfortunately implementing a custom solution like this is out of the scope of this forum as there are simply too many of them out there and we aren’t sure if all of them will work well.
I had a quick look and here is what I would suggest:
– Start by implementing the exact method from the solution like using <h2>Card</h2>
and see if you are able to get that work.
– Try just using HTML as suggested from scratch and don’t use GB with it.
If you aren’t still able to get it to work, then maybe consider a plugin like this?
https://wordpress.org/plugins/yoo-slider/