Spinner

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Loading Spinner'
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.ring:before {
  display: block;
  content: '';
  background: transparent;
  border: 3px solid rgba(0, 0, 0, .4);
  border-left: 3px solid rgba(0, 0, 0, .8);
  border-radius: 50%;
  width: 14px;
  height: 14px;
  position: absolute;
  top: 0;
  right: 0;
  animation: spin .8s cubic-bezier(1.0, 0.7, 0.9, 1.0) infinite;
  z-index: 10;
}

.ring {  
  background: transparent;
  box-shadow: 0 1px 1px rgba(0, 0, 0, .8);
 	width: 20px;
  height: 20px;
  border-radius: 50%;
  position: relative;
  z-index: 0;
}

.ring:after {
  display: block;
  content: '';
  background: transparent;
  box-shadow: inset 0 1px 1px rgba(0, 0, 0, .8);
 	width: 16px;
  height: 16px;
  border-radius: 50%;
  top: 2px;
  right: 2px;
  position: absolute;
  z-index: 20;
}

@keyframes spin {
  to {transform: rotate(360deg);}
}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<div class="ring"></div>
<br>
<br>

twiddle.json

{
  "version": "0.10.6",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.9.0",
    "ember-data": "2.9.0",
    "ember-template-compiler": "2.9.0",
    "ember-testing": "2.9.0"
  },
  "addons": {}
}