I am dead-set against all css packages that require classes in the HTML, thus creating lock-in. Now that HTML5 provides semantic tags, css should style tags. There are plenty of classless examples: see https://github.com/dbohdan/classless-css. The one I sometimes use is pico.css, but really I then just reference it to create my own css file optimized to what I want. But definitely no reason for new creators to allow themselves to be imprisoned by Bootstrap, Tailwind or any other class based package.