Issue #1013 <style> elements in HTML editor break editor's render method (#1017)
Issue #1013 <style> elements in HTML editor break editor's render method (#1017)

**Problem:** Calling `removeChild` on a non-child node throws an error.

**Fix:** The cheap solution here is to delete the content coming from the HTML editor first, then query all remaining `<style>` elements (coming from CSS editor and output base styles) and remove them from shadow root.
mdn/interactive-examples,mdn/interactive-examples,mdn/interactive-examples