Using minimal reproducer , Matt reports seeing duplicate CSS in devtools similar to what he reported in Hummingbird. CSS for the .pf-v6-c-drawer loads twice:

This is occuring because app is importing

import "@patternfly/patternfly/patternfly.css";

App should instead use

import '@patternfly/react-core/dist/styles/base.css';

We call out how to do it in core, but not react. Let’s modify the demo app to demonstrate this and add this information to the react-core package readme. and .

Jira Issue: PF-4452