I think you are point on. The two existing sibling comments have contradictory excuses for this: 1. New developers might know this, but standards change fast,

I think you are point on. The two existing sibling comments have contradictory excuses for this: 1. New developers might know this, but standards change fast, and it’s hard to keep up. 2. You can’t expect people new to the craft to know everything in the field. I personally found this article sub-basic. You could probably learn more and better on MDN. I think CSS might be one of few areas on HN where a sub-par article doesn’t get the constructive scrutiny it deserves in the top comments.