Slack example

application.controller.js

import Ember from 'ember';

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

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{first-comp class="first"}}
<br>
<br>

first-comp.component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

first-comp.template.hbs

<div class="middle">hello
{{second-comp class=class}}
</div>

second-comp.component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

second-comp.template.hbs

<div class="middle">
hi
</div>

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}
.first{
	border:1px solid black;
}
.middle{
  margin:5px;
  padding:5px;
}

twiddle.json

{
  "version": "0.6.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.3.1/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.3.3/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember-template-compiler.js"
  }
}