Funny Hugo,
This Sass code is extracted from your guidelines document:
$breakpoints: (
'medium': (min-width: 800px),
'large': (min-width: 1000px),
'huge': (min-width: 1200px),
);
As you can see, each value field in the outer map is a map itself whose key is an unquoted string data type in contradiction to your recommendation/advise here.
Maybe if you follow your own advise, we can then listen to you attentively.
What do you think?