Post-css-custom-media plugin with Sage 9 Beta 1

This question applies to adding additional post-css plugins to the new webpack workflow in sage. I’m specifically trying to get post-css-custom-media to work with the webpack setup in Sage 9 Beta 1.

I must admin that I’m still trying to wrap my mind around webpack, but I think I have the post-css-custom-media implementation correct. See lines 6 and 161: Pastebin |

I’m able to run builds without any errors, but the custom-css plugin doesn’t seem to be doing anything.

Thank you in advance for any insight or advice!