How can I enable sourcemaps?

I’d like to enable sourcemaps for .css files. How could I acclompish this? 
I’m currently using the theme:compile command to process the .scss files.

Hi John,

you will need to use the “hot mode” for psh:
./psh.phar storefront:hot-proxy

Then you will be able to see sourcemaps: 
https://github.com/shopware/platform/blob/66fd12c4e63f0641a724ed10bfd5e55553bd1d1c/src/Storefront/Resources/app/storefront/build/webpack.hot.config.js#L75

Kind regards,
Tim