You're right. I think we're on the same page. I was trying to get across the idea that CSS and visual presentation is a special case, peculiarly unsuited to DRY

You're right. I think we're on the same page. I was trying to get across the idea that CSS and visual presentation is a special case, peculiarly unsuited to DRY. Often visual features are only superficially similar ... e.g. at a certain stage in development the "Foo" component is superficially visually similar to the "Bar" component. If we then couple them together by both using the same CSS, but the implementation diverges as new features are added then we've given ourself a headache.