Vite Library Mode Is Not Excluding Classes

[incutonez]

I have a package that is pretty simple (see theme.zip), I have a theme.css file that adds a variable that I'll be using in consuming apps. All it exports is this theme.css file. This is what it looks like:

/* If I comment this out, then the build is as expected... no included Tailwind defaults */
@import "tailwindcss";

@theme {
    --color-select-200: var(--color-green-500);
}

The issue I'm having is when I run the build, it's including the Tailwind defaults and what's in my App.vue file, even though the App.vue, main.ts, and index.html are not included in the final output, as I'm excluding them in the vite.config.prod.ts file by using library mode. If I comment out the @import "tailwindcss" line, then I get the desired output, however, I can't do this because in reality, my actual theme relies on using PrimeVue's tailwind theming import, which relies on importing tailwind, and I need that to generate proper styles when doing a prod build.

So the question is, why are these extraneous styles being included in the final dist/theme.css file even though the files that are using them are excluded? This seems like a bug to me, but I wanted to ask here first, in case there was something glaringly obvious and stupid that I was doing.

[incutonez]

Dupe of #17025