I've had Open Props in here for a couple of weeks and it has been fun to simplify and rework what little CSS I had to use it.

My take is that Open Props provides a core set of custom properties mostly based around sets and scales that provide the building blocks to improve consistency of website implementation where it makes sense to have a defined set of available values. It also has some nice and sometimes whimsical presets for animations and gradients that bring a sense of fun (and usefulness) back to the web.

After working with Tailwind professionally for a year, one noticeable difference is that it is not an exhaustive set of properties for all possible attributes and being value based, there is not an entire new dsl on top of CSS to learn to use it.

I'm using the normalize bundle and it is super interesting using the :where() pseudo selector to prevent any specificity on the reset props.

It does mean you need to learn CSS (a good thing). And that all the tools and tricks to author maintainable CSS are still important.

But if there is a scale of values you need to have locked in. Or just have the choice made for you. Then Open Props is a pretty good starting place.