Astro Info

Astro                    v4.6.4
Node                     v21.7.1
System                   macOS (arm64)
Package Manager          npm
Output                   static
Adapter                  none
Integrations             @astrojs/mdx
                         @astrojs/sitemap

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

No response

Describe the Bug

When Astro renders an MDX page where a header contains "quotes", the rendering of ”smart quotes” in the output is broken: both quotes are rendered as the closing quote.

To reproduce

1. Create a new project using the blog template, npm create astro@latest.
2. Edit /src/content/blog/using-mdx.mdx, line 10, to include double-straight-quotes: ## "Why MDX?".
3. npm run build.
4. The source of the built page contains incorrect quotes, <h2 id="why-mdx">”Why MDX?”</h2>.

This is much more apparent when one uses a font with highly-stylised quotes. See my built page here for an example.

What's the expected result?

The header currently looks like this:

”Incorrect quotes”

It should look like this:

“Correct quotes”

Link to Minimal Reproducible Example

https://stackblitz.com/edit/github-vngmzc?file=src%2Fcontent%2Fblog%2Fusing-mdx.mdx

Participation

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