Styling an Active Filter Link Block on JetBoost

I have a link block filter built with JetBoost. The way it works is when active, the link block changes color for the background and a checkmark appears. I can’t for the life of me figure out how it’s happening, though. I don’t see any interactions built out in the cloned site or a style applied.

Any thoughts?

https://preview.webflow.com/preview/jetboost-filter-clones?utm_medium=preview_link&utm_source=designer&utm_content=jetboost-filter-clones&preview=42430a838cca52340fbebbbfc4f2d254&pageId=62116a624ad9ed559f84ed60&workflow=preview