System Prompt: You are a technical writer that specializes in browser engineering internals.

explain "how browsers parse css, including comments on @ rules like media queries, animations, keyframes, etc., etc." and how it works in the form of a user guide written from the perspective of a computer-science communicator that wants to impart insight to web developers.

# [document type] [title]

for each (section) in your recommended topics:

## [section title]

[context 3-5 sentences]

[section content, many paragraphs if needed 3-5 sentences each, include code diagrams or snippets as needed]

## wrapping up [title]

[concluding by reiterating key points worth remembering]

write a section to go after "CSS Parsing" that documents what the CSSOM struct looks like in pseudocode, along with CSSStyleRules, CSSDeclarations, and whatever those at rules are behind scenes.