content.code.annotate glitch with mermaid2

Reported at https://github.com/fralau/mkdocs-mermaid2-plugin/issues/88

This works

works # (1)

1. Annotations outside Mermaid blocks work fine

   ``` python
   works # (1)
   ```
   
   1.  this annotation works fine
   

This shows half the (+) button and nothing happens when you click it

1. this annotation doesn't open

<div class="annotate" markdown>
```mermaid
graph TD
A["Client (1)"] --> B[Server]
```
</div>

1.  this annotation doesn't open

Without the div, annotate does nothing

1. Without the div, annotate does nothing

```mermaid
graph TD
A["Client (1)"] --> B[Server]
```

1.  Without the div, annotate does nothing