Mermaid diagram in gist does not render in Obsidian

[Ben Hamilton]

Using the following

```gist
benhamilton/a9513a935c5cf5eb172cd189dfc5294a
```

in an Obsidian file, does not render the mermaid, we only get a blank screen.
This test gist is one of the examples supplied by Mermaid, and I've got it saved as a gist here: https://gist.github.com/benhamilton/a9513a935c5cf5eb172cd189dfc5294a

[Jun Lin]

Couldn't figure out a way to make the nested iframe work. 😞