GFM: collapsible sections not working

[vforvoid]

Hi there.

First of all, I want to say thank you for all the great work you did creating this theme.
I just started kicking the tires here and was wondering if the fact that GFM collapsed sections not working is expected behavior or a bug. It's not a part of a standard markdown and maybe you don't have any intention to support it.

I put this code into my post markdown file:

<details><summary>CLICK ME</summary>
<p>

#### We can hide anything, even code!

```ruby
   puts "Hello World"
```

</p>
</details>

And it got rendered like this in HTML:

[george-gca]

The easiest way I found for doing this is using the highlight liquid tag instead of pure markdown. Like this:

<details><summary>CLICK ME</summary>
<p>

#### We can hide anything, even code!

{% highlight ruby %}
   puts "Hello World"
{% endhighlight %}

</p>
</details>