BpDF principle of established presentational variation preferable to fixed presentation

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BpDF edition 1 lacks the kind of control for fixed presentation that are available in CSS/HTML and PDF, such as specifying specific fonts and font color. A BpDF principle for preferring established presentational variation means using markup/CSS that allows established presentational variation is preferable to markup/CSS that forces a particular presentation variation.

Examples of "established presentational variation" are:

• specific articles presented in a popular serif font in one venue and a popular sans-serif font in another venue
• web page text that flows to fit narrow screens widths or expands for wide screens and PDF files
• increasing font size by a reader
• white font color on black background (dark mode)
• GitHub-style vs Wikipedia-style inline code presentation

This is sometimes referred to as making markup/CSS more "semantic". "Semantics" in this case mean expected presentational variation based on existing establishes practice (in contrast to hypothetical imagined fictional future functionality).