Problem

Using the global attribute on a style block will prevent any use of composed CSS selectors inside it. Markup as simple as the following will trigger the error.

<style global>
    article :is(h1, h2) {
        font-family: "EB Garamond";
    }
</style>

Output

<redacted>/src/layouts/article.svelte:47:21 :global(...) must contain a single selector
 45 |      }
 46 |  
 47 |      :global(article) :global(:is(h1), :global(h2)) {
                            ^
 48 |          font-family: "EB Garamond";
 49 |      }

I would expect :global(article h1) :global(article h2) to be a more correct preprocessed output.