I'm getting $promise as a result for fetching css using $resource. Does anyone know how to resolve?

Getting $promise as a result of $resource.js

var app = angular.module('app', ['ngResource']);
app.service('fetch', ['$resource', function() {
  return $resource('css/:id/:file_name', {id: '@id'}, {
    'get': {
      method: 'GET',
      params: {
        file_name: 'style.css'
      }
    }
  }
}]);
app.directive('directive', ['fetch', function(fetch) {
  return {
    controller: function($scope) {
      $scope.click = function(id) {
        fetch.get({id: id}, function(result) {
          $scope.css = result;  // <<< this guy becomes $promise
        });
      }
    }
  }
});