Users are experiencing issues integrating Stitches into Shadow DOM due to its assumption of a global stylesheet. The request is for Stitches to adopt Constructable Stylesheets, with a fallback mechanism for browsers where they are not available.
**Is your feature request related to a problem? Please describe.** I've been trying to integrate stitches into shadow DOM, and have been running into issues since stitches assumes a global stylesheet with no easy way to insert it into a shadow root. **Describe the solution you'd like** Stitches adopt Constructable Stylesheets which can be used in the following manner: 1. Stitches can check if constructable stylesheets are available (Safari) or fallback to current behavior 2. `createStitches` provides a `CSSStyleSheet` object or `CSSStyleSheet[]` array 3. Stitches can apply styles to `document` via `document.adoptedStyles.push()` or user can opt out in the init to apply that same instance across roots themselves 4. when stitches modifies the styles it calls `CSSStyleSheet.replaceSync()` or `CSSStyleSheet.replace()` **Describe alternatives you've considered** I've been able to have 2 not-great solutions: 1. [[link]](https://lit.dev/playground/#gist=90e71187f33e35d