Install postcss-cssnext and replace every use of the rem mixin.
Compass' vertical-rhythm features (e.g. adjust-font-size-to) were very opaque, which led to misuse, and misunderstanding. Remove Compass entirerly, replace uses of its mixins with hardcoded declarations, and clean up uncovered duplciated declarations.
Convert obsolete single-column pseudo-element selectors to use the two-column syntax (or remove fallbacks) - e.g. :after => ::after.
remmixin.adjust-font-size-to) were very opaque, which led to misuse, and misunderstanding. Remove Compass entirerly, replace uses of its mixins with hardcoded declarations, and clean up uncovered duplciated declarations.:after=>::after.Note that autoprefixer is now used via cssnext.