New concepts
container-type, optional container-name, and @container width queries (including range syntax).
What changes after Design Tokens?
Chapter 11 taught viewport media queries. Tokens document shared breakpoints. Container queries let a reusable widget respond to the space it actually has.
Lessons
Checkpoint
Build one card component used in both a narrow aside and a wide main region. Use a single class and an @container rule so only the wide parent triggers the horizontal layout.