Get rid of PostCSS warnings during build process

[lunaceee]

I've been getting this warning message while compiling Heml files into HTML:

Without "from" option PostCSS could generate wrong source map and will not find Browserslist config. Set it to CSS file path or to "undefined" to prevent this warning.

I tried upgrading PostCSS version but the warning still exists. It's not harmful but it'll be nice to figure out how to get rid of it. I'm using Yarn for the build script.

Thanks a lot!

[ghost]

Hi,
This also happens for me using HEML build cli.