### Bug description

I have an issue when setting the background colours of titles and sub-titles.

It would appear that the specified colour is having some transparency applied.

In the snippet provided I can match the colours by altering the transparency of the subtitle to that in the commented out line.

````
---
title: 'A title'
subtitle: 'A subtitle'
---

```{=html}
<style>
  h1.title {
    color:white;
    background-color: #1b3445;
  }
  
  h1.title + p.subtitle {
    color: white;
    background-color: #1b3445;
    /*
    background-color: #1b3445e6;
    */
    margin-top: 0;
  }
</style>
```
````
<img width="285" alt="image" src="https://user-images.githubusercontent.com/43386915/235903690-f178226d-b4cc-4c22-9201-1bb3aa258b96.png">

---
title: 'A title'
subtitle: 'A subtitle'
---

```{=html}
<style>
  h1.title {
    color:white;
    background-color: #1b3445;
  }
  
  p.subtitle {
    color: white;
    background-color: #1b3445;
    /*
    background-color: #1b3445e6;
    */
    margin-top: 0;
  }
</style>
```

************************

- MacOS
    - Ventura 13.3.1
- Rstudio
    - RStudio 2023.03.0+386 "Cherry Blossom" Release (3c53477afb13ab959aeb5b34df1f10c237b256c3, 2023-03-09) for macOS
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) RStudio/2023.03.0+386 Chrome/108.0.5359.179 Electron/22.0.3 Safari/537.36
- Quarto v `1.3.340`
    - Have also checked v `1.4.25`

__Quarto check__

[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.2: OK
      Dart Sass version 1.55.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.4.25
      Path: /Applications/quarto/bin

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

[✓] Checking Python 3 installation....OK
      Version: 3.9.13 (Conda)
      Path: /usr/local/anaconda3/bin/python
      Jupyter: 4.11.1
      Kernels: python3

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

[✓] Checking R installation...........OK
      Version: 4.3.0
      Path: /Library/Frameworks/R.framework/Resources
      LibPaths:
        - /Library/Frameworks/R.framework/Versions/4.3-x86_64/Resources/library
      knitr: 1.42
      rmarkdown: 2.21

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


### Checklist

- [X] 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.
- [X] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [X] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] Please document the operating system you're running. If on Linux, please provide the specific distribution.
- [X] Please provide the output of `quarto check` so we know which version of quarto and its dependencies you're running.
dragonstyle
2023-05-03T11:44:17Z
jmcvw
bug
v1.4
closed
`background-color` in `.title` css class is overidden
https://github.com/quarto-dev/quarto-cli/issues/5393