Minor Principles of Design

See CSS2 Design Principles, Evolution of CSS Layout: Principles, Designing CSS slide deck for higher-level design principles.

Transparency Principle

Inserting an unstyled block in a block formatting context (as sibling, parent, child or intermediary) / unstyled inline in an inline formatting context should have no effect on styling.

Lea Verou Reordering Principle

If it can be unambiguously reordered, it should be reorderable.

Pass-through Auto-sizing Principle

`auto` as a size generally passes down any min/max-content constraints, and passes up through it the min/max-content contribution

Roc Principle of Spec-writing

If Robert O'Callahan is unhappy with your spec, you're the one who's wrong.