Rebuilds are only triggered from the css entry points

When using `ember serve` and `app/styles/app.css` as an entry point, rebuilds are only triggered when you make changes to `app.css`. So if you're importing css with rework-npm, and make changes to the imported css, they won't trigger a rebuild.

Is this something that can be solved from ember-cli-rework? I'd say it relates to ember-cli only watching the entry points, and not the partials (or at least not triggering a rebuild on the partials).