Sourcemaps in SvelteKit

Because of the various iterations, SvelteKit has gone through, it was pretty difficult to find out how to enable SvelteKit sourcemaps for CSS.

These days, sourcemaps are enabled through Vite, but you’re likely looking to enable sourcemaps during development, so build.sourcemap isn’t going to do anything for you.

What you need is config.css.devSourcemap:

// vite.config.ts
import { sveltekit } from '@sveltejs/kit/vite';
import type { UserConfig } from 'vite';

const config: UserConfig = {
    server: {
        port: 3000,
    plugins: [sveltekit()],
    css: {
        devSourcemap: true,

export default config;