CSS changes not showing up

Question

I have a Play 2.3.7 app configured with the sbt-web 1.1.0 plugin per the instructions under "Packaging and Publishing":

lazy val admin = Project("admin", file("admin")).
  enablePlugins(play.PlayScala, SbtWeb).
  settings(commonSettings: _*).
  settings(
    (managedClasspath in Runtime) += (packageBin in Assets).value,
    libraryDependencies ++= Seq(
      "org.apache.poi" % "poi" % "3.8",
      "org.apache.poi" % "poi-ooxml" % "3.8",
      "com.typesafe.play" %% "play-mailer" % "2.4.0",
      "org.scalatest" %% "scalatest" % "2.2.4" % "test"
    ),
    WebKeys.packagePrefix in Assets := "public/"
  )

This works fine when packaging and deploying (using sbt-native-packager). However, when run from SBT in development mode none of the changes made to any CSS show up until I completely exit and restart SBT (not even reload works). I am guessing that the CSS in the assets jar that is getting created is taking precedence. If I remove the (managedClasspath in Runtime) += (packageBin in Assets).value asset changes start working again BUT now none of the assets get deployed.

Is there a standard/idiomatic approach to fix this or I am stuck commenting and uncommenting lines in my build?