The easiest way to add the name of the current route as class to the body.

ember-body-class.js

Ember.Route.reopen({
  activate () {
    var classes = this.genClasses()

    if (classes !== 'application') {
      Ember.$('body').addClass(classes)
    }
  },
  deactivate () {
    Ember.$('body').removeClass(this.genClasses())
  },
  genClasses () {
    var classes = this.routeName.split('.')

    if (this.classNames) {
      for (var name of this.classNames) {
        classes.push(name)
      }
    }

    return classes.join(' ')
  }
})

https://medium.com/@leo/ember-adding-a-body-class-based-on-the-current-route-name-5d48cf16148f#.5x9fkcjpy