Include scss via hugo module

That’s not true (at least not for the /assts mount we’re talking about here). The Bootstrap project discovered that by accident …

That said, I would think that this should work:

[[module.imports]]
path = "github.com/sindresorhus/modern-normalize"
disable = false
[[module.imports.mounts]]
source = "modern-normalize.css"
target = "assets/scss/_modern-normalize.scss"

But then I don’t see your whole project.