Sass actually takes pains to make the source code it outputs readable. This isn't always entirely possible, since by its nature expressing something in Sass can

Sass actually takes pains to make the source code it outputs readable. This isn't always entirely possible, since by its nature expressing something in Sass can take significantly less code than the CSS counterpart and properly organizing the expanded code automatically is hard. But there are several output styles designed to be readable, and it's possible to add comments that are rendered as CSS comments.