Theming support

[mmailaender]

Hi @steven-tey,

Have you already thought about providing support for theming? So that every user of Novel can easily adjust Novel to their theme/corporate identity.

We have done that for our own with Novel, too. For that, we had to replace all Novel Tailwind classes with our Tailwind theme classes. We're using as our design system Skeleton.dev.

Skeleton is a Svelte UI library, but is assembled out of two major pieces:

1. A design system built up on TailwindCSS (Svelte independent - we're using it in our Nextjs projects)
2. The svelte specific UI components (don't needed in this context)

People could add their theme at this page https://www.skeleton.dev/docs/generator to get the theme config to set tailwind up with their custom theme. So Novel would be adjusted to the user's theme in under 10 minutes. Skeleton is also a dev dependency like tailwind, so it's not affecting the runtime bundle size.

If this sounds interesting to you, I'm happy to share more or to create a PR.

[mmailaender]

@steven-tey any thoughts on this?