Dynamic imported components - Stylesheets not getting inlined

[keshavdhawan281]

Describe the bug

As mentioned in sveltejs/svelte#15496

We were using inlineStyleThreshold to inline css before migration from svelte 4 to svelte 5. With this migration, we also updated sveltekit from 2.15.2 to the latest version.

This broke inline css for the cases where components are dynamically imported.

Came across this PR #13068
where we are filtering out dynamic imported stylesheets. But the case where components are dynamically imported during SSR, it should be considered to be inlined.

Reproduction

https://stackblitz.com/edit/sveltejs-kit-template-default-ethyrdbh

Logs

NA

System Info

NA

Severity

annoyance

Additional Information

No response

[dominikg]

please update the initial description to add the relevant information from the previous bugreport in svelte repo to help sveltekit maintainers quickly understand.

[keshavdhawan281]

Please provide an update on this. This is a blocker for our project. For now, we have downgraded sveltekit to 2.15.2 as a temp fix.

[paras-taneja]

One more observation here -

1. In SvelteKit version 2.16.1, the build was failing when using the inlineStyleThreshold configuration in svelte.config.js.

2. After upgrading to the latest version (@sveltejs/kit@^2.21.0), the build now completes successfully.

3. However, not all CSS files under the threshold are being inlined. While one larger CSS file (~30KB) was correctly inlined into the document, smaller styles (around 0.5KB to 2KB), especially those from Svelte component styles, are still being fetched separately instead of being inlined.