Copy/Passthrough css file with ember-cli-sass

I'm using ember-cli-sass with my ember app. Now I have a css file in the app/styles directory that I'd like to be copied to dist/assets (preferably minified but not necessary).

I've tried this in the build pipeline which gives a my-file.scss not found error

outputPaths: {
      app: {
        css: {
          'my-file': '/assets/my-file.css',
        }
      }
    }

and this which doesn't do anything

sassOptions: {
      passthrough: {
        include: ['app/styles/my-file.css']
      }
    }