rollup.config.js

plugins: [
        svelte({
            // enable run-time checks when not in production
            dev: !production,
            // we'll extract any component CSS out into
            // a separate file - better for performance
            css: (css) => {
                css.write("public/build/bundle.css")
            },
            preprocess: sveltePreprocess({
                postcss: true,
                scss: {
                    includePaths: ["src"],
                    postcss: {
                        plugins: [require("autoprefixer")],
                    },
                },
            }),
        }),
        // ...other plugins
]