New concepts
flex-wrap, flex-grow, flex-shrink, flex-basis, the flex shorthand, align-self, align-content, and order.
What changed after Phase 5?
Phase 5 gives boxes measurable, constrained sizes and safe overflow. Advanced Flexbox uses those sizes as inputs, then decides when items wrap and how positive or negative free space is shared.
Foundational prerequisites
Advanced lessons
Checkpoint
Create a wrapping card row. Give each card an intentional grow factor, shrink factor, and basis, then explain how the row responds when its available width changes.