Django collectstatic command is not able to compile animate.css

Question

I tried to use Animate.css in one of my Django Project (if interested here's the link).

Overview:
So to deploy the code, I run python manage.py collectstatic, as always. Till I don't include the animate.css in the {% styles css/base-min.css %} tag using django-sekizai and django-compressor together with the help of GIST.

The collectstatic just works fine, as soon as I include it in the project, the same command stucks.

For time being to use the animation.css in the project, I have directly included it with the help of

<link href="{{STATIC_URL}}/css/animate.min.css" 
      rel="stylesheet" 
      type="text/css" 
      media="screen" 
 />

But, the question remains, why is the collectstatic commands fails in general to compile the animate.css?