no syntax with code-block-bg

[musvaage]

Can one use ``` on code blocks absent a designation as to the coding language and still have the code block background colour render?

Syntax highlighting set for bash in the below shell output.

$ grep -A 10 format varehus.github.io/docs/blog/posts/2025-07-26-flutter/index.qmd
format:
  html:
    code-block-bg: "#f9fafb"
    code-copy: false
    other-links:
      - text: multilib
        href: http://www.slackware.com/~alien/multilib
    code-links:
      - text: alien-multilib-rsync.sh
        icon: file-code
        href: https://slackware.uk/~dive/scripts/alien-multilib-rsync.sh
$ 

[cderv]

Having background colors does currently requires the code block to have highlighting processing.

If you don't have a language to set, then you need to use default. Not setting any classes on the fenced code block will not add any highlight, and it does not responds to code-block-bg

Using obvious dummy color to see the effect here

---
format:
  html:
    code-block-bg: "#c50d0dff"
---

# No highlight

```
$ grep -A 10 format varehus.github.io/docs/blog/posts/2025-07-26-flutter/index.qmd
format:
  html:
    code-block-bg: "#f9fafb"
    code-copy: false
    other-links:
      - text: multilib
        href: http://www.slackware.com/~alien/multilib
    code-links:
      - text: alien-multilib-rsync.sh
        icon: file-code
        href: https://slackware.uk/~dive/scripts/alien-multilib-rsync.sh
```

# Highlight with no specific language

```{.default}
$ grep -A 10 format varehus.github.io/docs/blog/posts/2025-07-26-flutter/index.qmd
format:
  html:
    code-block-bg: "#f9fafb"
    code-copy: false
    other-links:
      - text: multilib
        href: http://www.slackware.com/~alien/multilib
    code-links:
      - text: alien-multilib-rsync.sh
        icon: file-code
        href: https://slackware.uk/~dive/scripts/alien-multilib-rsync.sh
```

If you want this a default, using a lua filter, you can automated the addition of .default to all CodeBlock with no class, and so this would apply to any code block like

```
code here
```

@gordonwoodhull we quickly spoke about this. There may be some redesign / fixes in how our styles applies on highlighted code block vs not highlighted; especially with brand impact. Maybe code-block-bg being set should apply to all code blocks...

[jimjam-slam]

The default highlighting style is a nice tip! I think I've manually styled a few code blocks in the past because they didn't have a supported language but I wanted the background.