[@astrojs/svelte] passing class to island component behaves differently from passing to static component

[JannikWempe]

What version of astro are you using?

1.4.6

Are you using an SSR adapter? If so, which one?

Vercel

What package manager are you using?

pnpm

What operating system are you using?

Mac

Describe the Bug

Passing a class prop from the outside into a Svelte component behaves differently if you assign client:something or not.

If I assign client:load the class prop is erased from the component. I just see a small blink where the class is applied before it's been erased.

How am I supposed to apply classes from a parent like that? Am I missing something?

Sidenote: I have encountered it applying margin via Tailwind classes but it is applicable to classes in general.

Link to Minimal Reproducible Example

https://stackblitz.com/edit/github-x1aahc?file=src/pages/index.astro

It works in Preact: https://stackblitz.com/edit/github-yudtcj?file=src/components/Counter.tsx

Participation

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

[matthewp]

Looks like this was added here: https://github.com/withastro/astro/pull/1406/files#diff-0bac01b129c0097c2262479a0cf79644ef556ba4cc69f0e8ef5874de2a06c2be. Not sure why. Seems wrong. Think we can remove it.