I just started digging into Bulma, and ran into https://github.com/jgthms/bulma/issues/1836 . It turns out you shouldn't use Bulma if you actually want h1, h2, and similar semantic elements to do anything. The default Bulma styles make h1, h2, and various other elements all look identical to normal body text, unless they have Bulma CSS classes applied to them.

On top of that, it uses CSS classes for things like "this button is rounded" (https://bulma.io/documentation/elements/button/#styles) or "this tab bar has borders around its tab labels" (https://bulma.io/documentation/components/tabs/#styles).

The kind of CSS framework I expected was one that provides semantic classes for things like tab bars and similar, and then themes can decide things like "my tab bars should have borders around their tab labels". (And, as a side effect, the CSS would also be smaller, since it only needs a style for "tab bar", and not "tab bar without is-boxed" and "tab bar with is-boxed".)