@U66G3SGP5 https://bulma.io is my favorite so far for css. There is reakit in fulcro incubator, so guessing it plays really nice with fulcro, might be worth taking a look https://github.com/fulcrologic/fulcro-incubator/blob/develop/README.md

Bootstrap works fine, and there is a bootstrap ns in fulcro that wraps most active components…it’s a bit alpha, but would be easy to improve. I’ve also had good luck with semantic UI.