Are you migrating one element at a time, or a whole app?
The best way to do style sharing with LitElement is to use static styles:
share-styles.js:
export const sharedStyles = css`
h1 { color: blue; }
`;
element.js:
import {sharedStyles} from './shared-styles.js';
export class MyElement extends LitElement {
static get styles() {
return [sharedStyles, css`
:host {
display: inline-flex;
}
`];
}
}
If you're migrating incrementally and need to use Polymer shared styles, I think you'll need to use the DomModule class to find the style sheet. I can look up some code for you if this is the case.