WEll, I wrote a functional CSS framework that is platform agnostic. It was built on sass. Post: https://www.minid.net/2019/4/7/the-css-utilitarian-methodolo..., github https://github.com/meerita/utilcss I am working a different project now, and now I evolved it to simply pure css files that i compile later with postcss and purge everything.

I think the approach is noble but by looking at their own website, just the H1 has this:

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Just-in-time CSS, unlimited possibilities

I think that is spaghetti code. I can do that with my own library and much cleaner functional approach, and much reduced code https://github.com/meerita/utilcss

I don't use a lot of animations, if it's simple stuff I'll just do it myself. Have used animate.css before, it was quite nice, especially paired with wow.js. Have been meaning to try AnimXYZ but again, don't use a lot of animations so haven't been able to yet.

Vue handles it just fine with doing the hard work behind the scenes and just passing you some CSS classes to connect your animations to (and there are JS events to use as well if you need a JS animation). Main difference is Svelte gets the benefit of being able to do some fancier stuff like items changing order or doing more than just entering/exiting. Vue has this as well, but not as easy to use.

That being said I overall prefer the Vue CSS approach to animation, it inspired my brother and I to make https://animxyz.com which has been my most successful side project yet. We wanted to make it work for Svelte as well but they don't have the CSS classes so we can't hook into their events the same.

GSAP seems like overkill, these are simple css animations, animXYZ could do the heavy stuff for you but it shouldn't take that long to learn.

Documentation | GitHub

Slightly off topic, but I'd also recommend checking out AnimXYZ and has Vue-specific support.

Animxyz A tool that helps you create, customize, and compose animations powered by CSS variables without custom keyframes.

Adding animations to a web app can be a challenging task, so it’s natural to reach for a library to make it easier. AnimXYZ, a composable CSS animation toolkit, allows you to compose complex animations by combining simple utility classes.

AnimXYZ

Animxyz for Animations and Transitions

Have used animate.css in the past, was very nice and easy to work with. Animista and animXYZ seems cool too.