[EDIT] - BTW, I mean this with less snark and more did-you-know-all-these-existed? I knew of purecss & skeleton (and I've forgotten a few, because it used to be very common to see these), and I've seen bulma before but some others were new to me (and I favorited them to give a try on some random project)
PureCSS was one of my favorites for a very long time. These days I use component frameworks like ElementUI[0] more than anything else to maintain consistent styling (since most things on the page happen to be components).
http://getskeleton.com/
https://tachyons.io/
https://bulma.io/
https://picnicss.com/
https://www.muicss.com/
[EDIT] - BTW, I mean this with less snark and more did-you-know-all-these-existed? I knew of purecss & skeleton (and I've forgotten a few, because it used to be very common to see these), and I've seen bulma before but some others were new to me (and I favorited them to give a try on some random project)