Not rendering equations properly

[juansqw]

I'm using this theme for a small project and I'm trying to add equations to one of my posts.

Here's what I have:
$$
\pi_t = \frac{P_t - P_{t-12}}{P_{t-12}} = \frac{226.40 - 188.09}{188.09} = 0.2036
$$

However, when rendering, it does not show the equation properly.

I have tried with other themes and they work fine. My guess is that it has something to do with the /layout/partial/foot_custom.html file (which is missing).

Any help?