Semantic
The bar renders before the Scaffold body on every target.
FIXED SHELL
A viewport-fixed application bar
This AppBar remains anchored to the viewport while the Scaffold main region scrolls beneath it.
Boxed content
The bar stays full width while its regions use a centered reading width.
Portable
The same region order lowers to web, Android, and iOS.
Scroll the shell
Additional content makes the relationship between the AppBar and Scaffold visible inside the embedded example.