MathJax on Ghost

Question

I have been trying to add MathJax to my blog in the "Ghost" platform on the web (not self hosted). I followed some tutorials and I did find out that if I add the code

<script type="text/javascript">
MathJax.Hub.Config({tex2jax: {inlineMath: [ ["$","$"] ], displayMath: [ ["$$", "$$"] ]}});
</script>
<script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML">
</script>

into the "blog header" (that I find in "settings"->"code injection") MathJax works fine for displayed math formulas written between $$. On the other hand there is no way to have the inline math rendered: it doesn't work with the code $...$, (...) and [...]. What am I doing wrong?

Here is my test post on the platform.