Personally I'm happy using Bulma with Svelte. I find most UI libraries tend to add too much bloat so I'd rather have something that only adds configurable CSS and just add as much JS as I need/want.
I used Vue+Vuetify some years ago. I wasn't very happy with it, but I agree Svelte needs something similar.
There are a couple of projects out there that add Svelte components for Bootstrap, Material, or IBM Carbon you could check.
https://github.com/bestguy/sveltestrap
https://github.com/carbon-design-system/carbon-components-sv...
There are also a couple of projects about headless (no CSS) components for Svelte although I only seem to be able to find this one (not public yet)
I guess something like Tailwind Headless (only available for React and Vue):
As a side note, Tailwind UI does include some components that require JS--that's what the Headless UI library is for. But it's also true that it's not a comprehensive component library; still missing things like a combobox or a date picker.
What takes 10 seconds and 20 chars in Vuetify takes 10~100 minutes and multiple components/sub-components written by hand in Tailwind in Svelte.
Of course talking about Tailwind isn't Svelte/SvelteKit specific: I just couldn't find a remotely comparable UI library for Svelte so I gave up and stuck with Tailwind to get the project done.