Mermaid fig-width no longer works

Bug description

Following the documentation on sizing mermaid diagram, the latest nightly build (1.3.107) running on Ubuntu 20.04 no longer sizes the diagrams differently regardless of the fig-width parameter. I also tried this with the latest stable (1.2.313) and it has the same issue.

For example, in the following script the diagram under #Slide 1 is the exact same size as the diagram in #Slide 2. I have tried playing with both and fig-width and fig-height but neither seems to have any effect.

---
title: Bad Mermaid Sizing
format:
    revealjs
---

# Slide 1

```{mermaid}

%%| fig-width: 5

flowchart LR
  A[Hard edge] --> B(Round edge)
  B --> C{Decision}
```

# Slide 2

```{mermaid}

%%| fig-width: 15

flowchart LR

  A[Hard edge] --> B(Round edge)
  B --> C{Decision}
```

Maybe related to some of the fixes for https://github.com/quarto-dev/quarto-cli/issues/2607?

Checklist

• Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
• Please format your issue so it is easier for us to read the bug report.
• Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
• Please document the operating system you're running. If on Linux, please provide the specific distribution.