From the official guide: "This document defines formatting and style rules for HTML and CSS.
It aims at improving collaboration, code quality, and enabling supporting infrastructure.
...like other Google style guides, deals with a lot of formatting-related matters.
It also hints at best practices so to encourage developers to go beyond indentation.
Many style guide authors know the underlying motivation from the question whether to describe the code they write—or to prescribe what code they want to write. Not surprisingly then, in our HTML and CSS style guide you’ll find both (as much as you’ll still find a lot of different development styles in our not entirely small code base)."