A method for easily stacking multiple icons. Use the fa-stack class on the parent and
fa-stack-base for the bottom icon.
fa-twitter on fa-check-empty
fa-flag on fa-circle
fa-terminal on fa-sign-blank
fa-camera on fa-ban-circle
{% highlight html %}
fa-twitter on fa-check-empty
fa-flag on fa-circle
fa-terminal on fa-sign-blank
fa-camera on fa-ban-circle
{% endhighlight %}