This appears to be the same issue as plone/plone.app.event#283 but with that css having moved over to this package. I know @thet fixed it at one point and then it was removed entirely. Should the plone-app-event resource even exist as part of the plone-legacy bundle by default? It looks like plonetheme.barceloneta handles event styling so I'm not clear what purpose this css resource serves anymore, or why it should live in the legacy bundle.