`define:vars` not working with `is:inline` directive in `<style>` tags

[jacobdalamb]

Astro Info

Astro                    v4.5.9
Node                     v18.18.0
System                   Linux (x64)
Package Manager          npm
Output                   static
Adapter                  none
Integrations             none

If this issue only occurs in one browser, which browser is a problem?

No response

Describe the Bug

According to the Astro documentation, the define:vars directive should allow passing server-side variables from the component frontmatter into the <style> tags. The documentation does not mention any specific limitations or incompatibilities between define:vars and is:inline for <style> tags.

What's the expected result?

When using the define:vars directive in a <style> tag that also has the is:inline directive, the variables passed through define:vars do not seem to be properly injected or accessible within the styles. The styles do not apply as expected, and there is an error message but goes away once the page is reloaded.

Link to Minimal Reproducible Example

https://stackblitz.com/edit/github-zbqqwf?file=src%2Fpages%2Findex.astro

Participation

• I am willing to submit a pull request for this issue.

[lilnasy]

is:inline skips processing steps. The magic done by define:vars is a processing step. So it is not expected work.

However, the effect of the two together should be that a style tag with the attribute `define:vars is rendered. This does not happen, either - invalid CSS is generated instead. That's something to fix.

We could add a warning through our editor tooling as well.

[lilnasy]

For this input:

<style is:inline define:vars={{ textColor: foregroundColor, backgroundColor }}>
  h1 {
    background-color: var(--backgroundColor);
    color: var(--textColor);
  }
</style>

The compiler outputs:

$$render`<style>${$$defineStyleVars({ textColor: foregroundColor, backgroundColor })}
  h1 {
    background-color: var(--backgroundColor);
    color: var(--textColor);
  }
</style>`

...which renders a non-parseable inline stylesheet.

It should output code that renders define:vars as an attribute. define:vars is a skipped attribute. It would be more trouble than its worth to output it verbatim.