Confusion around how to add and use CSS classes

Hi!

I'm going through [the docs](https://github.com/BuilderIO/mitosis/blob/main/docs/components.md#class-vs-classname) and find it says to use 'class' over 'className' which is fine.

Currently I can't see any documentation on where to put my class styles. Is using an external .css file possible ? Or styled components? Just need some info and example code on how to set this up please.

Secondly I tried using the `css` prop and using the exported component in React, but it just renders to '[object Object]' in the DOM :

seeker.lite.tsx:

`

Start with docs/components.md#class-vs-classname, then reproduce the example from seeker.lite.tsx and compare the generated seeker.jsx and React DOM output. Review how the css prop is handled and document supported external CSS or styled-component usage, with examples and corrected or clearly explained React output as the done criteria.

Written by the indexing model from the issue text.