Inject Styles into Lit component with Constructible Stylesheets

index.ts

// before we add our component to the DOM
// we are going to alter the rh-cta definition
// this will alter the stylesheet for all CTAs
await customElements.whenDefined('rh-cta').then(() => {
  const RhCta = customElements.get('rh-cta');
  if (!RhCta) { return; }
  const styles = RhCta.styles?.[0].styleSheet as CSSStyleSheet;
  styles.insertRule(`
    ::slotted(a) { white-space: normal !important; }
  `, styles.cssRules.length);
});