Testing my Postie Setup: Act 2. Mermaid, LaTeX, Images

Mermaid

sequenceDiagram Alice->>John: Hello John, how are you? John-->>Alice: Great! Alice-)John: See you later!

LaTeX

$$ \left[ \begin{matrix} 1 & 0\\ 0 & 1 \end{matrix} \right] $$

An Image