And here is some display math:
\[\int_0^\infty \theta e^{-\theta x}\, dx = 1\]Here is some inline math. $f(x) = \theta \exp\p{-\theta x}$.
\[\begin{aligned} X_i &\ind \text{Exponential}(\theta) \\ \bar{X} &\overset{\cdot}{\sim} \text{Normal}(\theta^{-1}, \theta^{-2}/n) \\ \end{aligned}\]Also, note that I am using the Fira Sans
font, and not the default KaTeX
(serif) math font.