Update README.md

README.md

@@ -6,18 +6,19 @@
 
 ## Local development
 
-Requires Node.js (`node`), Python (`python3`), and Java (`java`). It is known to work in these environments but should work in others:
+Requires Node.js (`node`), Python (`python3`), and Java (`java`). It is known to work in these environments but should work in many others:
 
- - Windows 10, Python 3.11.7 (Microsoft Store), Node.js 20.10.0 (nodejs.org installer), Java 11 (Temurin-11.0.21+9)
  - Windows 10, Python 3.12.1 (Microsoft Store), Node.js 20.10.0 (nodejs.org installer), Java 11 (Temurin-11.0.21+9)
+ - macOS 14.2.1, Python 3.11.6 (Apple), Node.js 20.10.0 (installed manually), Java 21 (Temurin-21.0.1+12)
+ - Ubuntu 22.04, Python 3.10.12 (python3 package), Node.js 20.10.0 (installed manually), Java 11 (openjdk-11-jre package)
 
 Install dependencies:
 
 ```sh
 npm ci
 ```
 
-Open tests/vertical_playground.html in a browser for local testing. You don't need to rebuild compressed versions for most changes.
+Open tests/vertical_playground.html in a browser for development. You don't need to rebuild compressed versions for most changes. Open tests/vertical_playground_compressed.html instead to test if the compressed versions built properly.
 
 To re-build compressed versions, run: