### Bug description

Adding the following to the YAML of the template Quarto Document results in source code that is too light to be legible.

``` yaml
format: 
  html:
    code-tools: true
    highlight-style: a11y-dark
```

<img width="1552" alt="Screen Shot 2022-07-12 at 6 59 10 PM" src="https://user-images.githubusercontent.com/5965649/178654546-99f28b1b-f9b9-4ee2-b97d-c59f81e652f7.png">

- Quarto version: 1.0.16
- OS: macOS 12.4
- RStudio: RStudio 2022.07.0+548 "Spotted Wakerobin" Release (34ea3031089fa4e38738a9256d6fa6d70629c822, 2022-07-06) for macOS Mozilla/5.0 (Macintosh; Intel Mac OS X 12_4_0) AppleWebKit/537.36 (KHTML, like Gecko) QtWebEngine/5.12.10 Chrome/69.0.3497.128 Safari/537.36

### `quarto check` Output

```
[✓] Checking Quarto installation......OK
      Version: 1.0.16
      Path: /Applications/quarto/bin

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

[✓] Checking Python 3 installation....OK
      Version: 3.10.1
      Path: /usr/local/bin/python3
      Jupyter: 4.9.1
      Kernels: python3

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

[✓] Checking R installation...........OK
      Version: 4.2.0
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Users/mine/Desktop/RStudio/quarto-tip-a-day/renv/library/R-4.2/x86_64-apple-darwin17.0
        - /Library/Frameworks/R.framework/Versions/4.2/Resources/library
      rmarkdown: 2.14

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

### `quarto tools check` Output

```
Tool         Status                    Installed     Latest  
chromium     Not installed             ---           869685  
tinytex      External Installation     ---           v2022.07
```

### Checklist

- [X] [formatted your issue](https://yihui.org/issue/#please-format-your-issue-correctly) so it is easier for us to read?
- [X] included 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.
- [x] documented the quarto version you're running, by pasting the output from running `quarto check` in the "Quarto Check Output" text area?
- [x] #1374
- [X] documented the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] documented which operating system you're running? If on Linux, please provide the specific distribution as well.
- [X] upgraded to the latest version, including your versions of R, the RStudio IDE, and relevant R packages?
2022-07-13T05:06:22Z
mine-cetinkaya-rundel
bug
closed
Highlighting code-tools source code not legible with highlight-style: a11y-dark 
https://github.com/quarto-dev/quarto-cli/issues/1370