Scalacss issue

ExampleStyle.scala

package foobar.style

import scalacss.Defaults._

object ExampleStyle extends StyleSheet.Inline {
  import dsl._

  val ul = style(
    backgroundColor.blue
  )

}

Index.scala

package foobar.page

import foobar.style.ExampleStyle

import scalacss.Defaults._
import scalacss.ScalatagsCss._
import scalatags.Text._
import scalatags.Text.all._
import scalatags.Text.tags2.title

object Index {

  val page =
    html(
      ExampleStyle.render[TypedTag[String]],
      title("FooBar"),
      head(),
      body(
        h1("FooBar"),
        TopNav.page
      )
    )

}

Server.scala

package foobar

import foobar.page.Index
import org.http4s.HttpService
import org.http4s.MediaType.`text/html`
import org.http4s.dsl._
import org.http4s.headers.`Content-Type`
import org.http4s.server.ServerApp
import org.http4s.server.blaze._

object Server extends ServerApp {

  val service = HttpService {
    case GET -> Root => Ok(Index.page.render).withContentType(Some(`Content-Type`(`text/html`)))
  }

  def server(args: List[String]) = BlazeBuilder.bindHttp(8080)
    .mountService(service, "/")
    .start
}