- if the author decides to let the text flow (depending on the width of the parent container), it must do so without disturbing line numbering
- line numbers must not be hardcoded
- numbers must appear in a "gutter"
- text resizing must not break the layout nor disturb line numbering
- markup must be semantic (no structural hack)
- markup must be "hook free" (no
ID, no CLASS) - CSS must be plain and simple

Your web developers will overflow their box model when they see you sporting this hilarious new t-shirt! Then they'll go back to using tables.