How to use autoprefixer with svelte?

Question

I've tried to piece together how to get autoprefixer to work in svelte from the few posts hanging about but have been unsuccessful.

I ran npm install postcss postcss-cli autoprefixer in my root directory and my package.json now has

"dependencies": {
    "autoprefixer": "^10.4.14",
    "postcss": "^8.4.25",
    "postcss-cli": "^10.1.0",
    // some other stuff
}

Then i modified my svelte.config.js to

import sveltePreprocess from "svelte-preprocess";
import autoprefixer from "autoprefixer";

export default {
    preprocess: sveltePreprocess({ postcss: { plugins: [autoprefixer()] } }),
};

I created a postcss.config.js file in the root folder and put inside

module.exports = {
    plugins: {
        autoprefixer: {},
    },
};

I also created a .browserslistrc file in root folder and put in it

> 1%

Then i ran npm run dev. However, when i look at bundle.css, there are no vendor prefix css properties. How can i get this to work?