A html-defaults style property is added to doc, unless doc’s style already has a html-defaults style property (e.g., supplied to title). Similarly, a latex-default style property is added if one is not already present. Finally, an css-style-addition property is always added.
For HTML rendering:
The file "manual-files.css" from the "scribble" collection is designated as an additional accompanying file in html-defaults.
The file "manual-racket.css" from the "scribble" collection is added as a css-style-addition.