Update upgrade CLI to handle containers config correctly (#16169)

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Nothing yet!
 
+### Fixed
+
+- Ensure that the `containers` JS theme key is added to the `--container-*` namespace. ([#16169](https://github.com/tailwindlabs/tailwindcss/pull/16169))
+
 ## [4.0.3] - 2025-02-01
 
 ### Fixed

packages/tailwindcss/src/compat/apply-config-to-theme.ts

@@ -151,6 +151,7 @@ export function keyPathToCssProperty(path: string[]) {
   if (path[0] === 'borderRadius') path[0] = 'radius'
   if (path[0] === 'boxShadow') path[0] = 'shadow'
   if (path[0] === 'colors') path[0] = 'color'
+  if (path[0] === 'containers') path[0] = 'container'
   if (path[0] === 'fontFamily') path[0] = 'font'
   if (path[0] === 'fontSize') path[0] = 'text'
   if (path[0] === 'letterSpacing') path[0] = 'tracking'