Is Bootstrap really used in this component? It probably is, and I've just missed it.

For other components like spark-button, we've used a half-baked attempt to externalize Bootstrap styling: bootstrap.css is included in ide/app/spark*.* and spark-button just uses it, and so can spark-suggest-box. The idea is that a user of widgets could use their own CSS with a subset of class names analogous to Bootstrap's, and thus style the widgets differently. I'm not sure whether we'll want to try to complete this story or give up and make the widgets anapologeticaelly Bootstrap-based. But in the meantime, let's remove these `@imports` here to keep the widgets in-sync.