Make sure you have Polyserve and Web Component Tester installed.
yarn install -g polyserve web-component-tester
yarn start
yarn run test
yarn run build
Run yarn start and Polyserve will start a server and open your default browser to the demo page of the element.
Button (and all RHElements) use Prettier to auto-format JS and JSON. The style rules get applied when you commit a change. If you choose to, you can integrate your editor with Prettier to have the style rules applied on every save.