css sourcemap broken

[magicly]

I did as the readme file, but cannot see css sourcemap in Chrome. In fact, it shows "bundle.css:1".

The css sourcemap seems broken, but in REPL it is ok.

I'm a newbie for Svelte so maybe I miss sth. Any help is welcome, thanks~

my svelte is"version": "3.31.2"

[magicly]

https://github.com/sveltejs/sapper-template-webpack is ok, but https://github.com/sveltejs/sapper-template-rollup is not. It seems sth wrong with rollup's config?