You cannot use an import inside a template today to load CSS scoped to your element, that's known not to work.
Your original idea of using simple old link pointing to bootstrap.css
is the way to go, the notion is that user agent is supposed to be smart enough to share that CSS.
We consider the double loading you sometimes see today a browser bug. If you can live with it temporarily, that's the way to go. Unfortunately bootstrap.css
was not written with scoped CSS in mind, so it magnifies this problem more than custom CSS would.