New Twiddle

components.card-component.js

import Ember from 'ember';

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

components.super-card-body-component.js

import Ember from 'ember';

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

components.super-card-component.js

import Ember from 'ember';

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

components.super-card-title-component.js

import Ember from 'ember';

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

controllers.application.js

import Em from 'ember';

export default Em.Controller.extend({
  name: 'alex',
  
  badTitle: Em.computed('name', function() {
    let name = this.get('name');
    return Em.String.htmlSafe(`hi <b>${name}</b>!!`);
  })
});

styles.app.css

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

.title {
  background-color: yellow; 
  padding: 10px;
}

.body {
  background-color: lightgreen;
  padding: 10px;
  min-height: 100px;
}

templates.application.hbs

<h2>Card Component:</h2>

name: {{input value=name}}
<hr />

{{#card-component title="This can't have HTML"}}
  <h3>content</h3>
{{/card-component}}

<hr />

{{#card-component title=badTitle}}
  <h3>content</h3>
{{/card-component}}

<hr />

{{#super-card-component as |card|}}
  {{#card.title}}
    hi <b>{{name}}</b>!
  {{/card.title}}
  
  {{#card.body}}
  	<h3>content here</h3>
  {{/card.body}}
{{/super-card-component}}

<hr />

{{#super-card-component title="this is the title" as |card|}}  
  {{#card.body}}
  	<h3>just the body</h3>
  {{/card.body}}
{{/super-card-component}}

templates.components.card-component.hbs

<div class="title">
  {{title}}
</div>

<div class="body">
  {{yield}}
</div>

templates.components.super-card-body-component.hbs

<div class="body">
	{{yield}}
</div>

templates.components.super-card-component.hbs

{{#if title}}
  {{super-card-title-component title=title}}
{{else}}
  {{yield 
    (hash 
      title=(component 'super-card-title-component')
    )
  }}
{{/if}}

{{yield
  (hash 
    body=(component 'super-card-body-component')
  )
}}

templates.components.super-card-title-component.hbs

<div class="title">
	{{#if hasBlock}}
		{{yield}}
  {{else}}
  	{{title}}
  {{/if}}
</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"
  }
}