New Twiddle

controllers.application.js

import Ember from 'ember';

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

styles.app.css

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

.thing {
  background: #eee;
  cursor: pointer;
  padding-bottom: 4px;
  position: relative;
  text-align: center;
  width: 200px;
}

.thing::after {
  background: #f60;
  bottom: 0;
  content: ' ';
  display: block;
  height: 4px;
  left: 50%;
  position: absolute;
  transition: left .3s ease-in-out, width .3s ease-in-out;
  width: 0;
}


.thing:hover::after {
  left: 0;
  width: 100%;
}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

<div class="thing">Hello</div>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}