Mermaid diagrams in `typst` don't get brand colors

Bug description

When a mermaid diagram is used in format: typst, the PNG that gets generated doesn't have the same SCSS/CSS applied that the HTML version does. The result is a diagram where the colors don't follow brand.

Steps to reproduce

---
title: "Untitled"
format: 
  html: default
  typst: default
brand:
  color:
    background: "#000"
    foreground: "#fff"
    primary: "#f19710"
---

```{mermaid}
%%| fig-width: 6.5
flowchart LR
  A[Hard edge] --> B(Round edge)
  B --> C{Decision}
```

Expected behavior

The PNG used in typst should look like the HTML version of the diagram:

Actual behavior

The PNG used in typst has default colors:

Your environment

Mac OS 15.0

Quarto check output

quarto check
Quarto 99.9.9
[✓] Checking environment information...
      Quarto cache location: /Users/charlottewickham/Library/Caches/quarto
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.4.0: OK
      Dart Sass version 1.70.0: OK
      Deno version 1.46.3: OK
      Typst version 0.11.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 99.9.9
      commit: bf1664b7ac3049d3775c1eada99bb6841ed9505c
      Path: /Users/charlottewickham/Documents/posit/quarto-cli/package/dist/bin

[✓] Checking tools....................OK
      TinyTeX: v2024.03.13
      Chromium: (not installed)

[✓] Checking LaTeX....................OK
      Using: TinyTex
      Path: /Users/charlottewickham/Library/TinyTeX/bin/universal-darwin
      Version: 2024

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.12.1
      Path: /Users/charlottewickham/Documents/posit/quarto-web/.venv/bin/python
      Jupyter: 5.7.2
      Kernels: julia-1.10, ark, python3

[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........OK
      Version: 4.3.3
      Path: /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources
      LibPaths:
        - /Users/charlottewickham/Library/R/arm64/4.3/library
        - /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/library
      knitr: 1.45
      rmarkdown: 2.28

[✓] Checking Knitr engine render......OK