My favourite for small projects (the only kind of project I do ^^) is Pure.css [0]. It is wonderfully small, about 1/20th of the size of Bulma. Small enough to actually read and understand.
This is the first time I've heard of the Yahoo! BSD License. It was an improvement when the original BSD license dropped conditions, so this seems like a step backwards, license-wise.
[0]: https://purecss.io/