FrontendHaltCSS·Beginner·Conceptual·1 min read
Does margin participate in either box-sizing model?
Short interview answer
No. Margin is always outside both the content-box and border-box calculations; it affects spacing between elements and can collapse with adjacent block-level vertical margins, but it never changes the box's own declared size.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.