Colors in code view are coding (and mis-codeing warnings

)
Black is your text. (When IN THE BODY) It may required when in the Headers, best leave it unless you know what you are breaking
Blue are Tags
dark green comments (includes commented OUT text)
Gold is (local to the page) Style(?) SGC stuff and @page are inserted by Sigil
Red is tag attributes, the teal is the value to be passed
I may have missed some less common.