It can be confusing using a style guide, alongside the rules of punctuation and grammar.
Our proofreading and editing course advises that the style guide does not cover punctuation and grammar – unless they have to be used in a particular way.
In other words, the rules of punctuation take precedence, unless the style guide says otherwise.
For instance, the Guardian guide has a section on brackets under B. These supercede the normal rules of punctuation.
when you are doing a proofreading job, you should check if the style
guide has any rules on punctuation, and follow them. And the same with
We also tell students on our proofreading and editing courses that some clients do not follow the correct rules of punctuation – and they are right, even when they appear wrong!
This article explains this very well.
Online proofreading courses