This appears to be a really nice little CSS framework, but what I love about it is how similar it is to the frameworks I've written code for recently. For instance, even the partial one I put together for this blog has color & spacing methods in Sass that translate to CSS variables - and Spruce has the same concepts, just with different names.

One reason I can be wary of adopting third-party CSS frameworks is that they just work differently than I'm used to - I have to change how I think, and not necessarily for the better. That doesn't seem to be the case with Spruce, and I love that.