What files from a theme do and do not need to be included in the Static directory?

Hi folks, I’m just getting past the basics with Hugo and had this point of confusion come up. I notice that, after setting up and validating a theme for my site, that the tutorial I was following copied the stylesheet from the theme directory to the site’s Static directory. I understand that the static directory is for non dynamic assets to be included in the site build, but I also noticed that the website preview, before building, seemed to be able to read the stylesheet straight from the theme directory.

Am I typically able to edit theme directories directly, or generally should I move those files into my site structure (like into /static) before editing them? When building the site, what files don’t need to be moved to the site structure to be included in the build?

My general confusion lies with what pieces of the theme directory are included when building, versus when I need to manually move something to a directory like /static.

Thanks!

This may be helpful:
https://gohugo.io/quick-reference/glossary/#component

The unified file system allows you to, for example, override proejct/themes/my-theme/static/style.css with project/static/style.css. Always override theme files; do not replace them. That allows you to easilty update the theme in the future.