I have a pure vanilla webcomponent, lets call it "Spinner.js" and a "Spinner.css". Can I bundle this to just one JS-File including
the CSS file?.

Currently my rollup configuration looks like this, but CSS ins not bundle inside *.JS File

const bundle = await rollup({
		input: `${webcomponent.pathToWebcomponent}`,
		plugins: [nodeResolve(), commonjs(),postcss({
			extract: false,
			minimize: true,
			inject: {
				insertAt: 'top',
			},
		}), terser()],
	})