cd my-libraryyarn installyarn buildcd ../my-exampleyarn installyarn test
The following console error should be shown:
Error: Could not parse CSS stylesheet
run yarn dev in the my-example directory and go to the created server.
When you inspect the html you will see this html attribute
<style data-styles="">{visibility:hidden}.hydrated{visibility:inherit}</style>
Containing the css without a selector.
Calling defineCustomElements multiple times injects css without a selector.