- styles.ts: adoptStyles(root, css) adopts a constructed stylesheet into a shadow root or document
(not governed by a page's CSP, parsed once, stays with the root when its host is moved);
<style> fallback where constructable sheets are missing or refused.
- UI kit: the kit's shadow root and each dialog's `css` use it (dialog CSS goes with the dialog).
- Plugin API: api.adoptCSS(root, css) and scope.adoptCSS (removed on dispose); injectCSS keeps its
<style> and, when a CSP leaves it without a sheet, applies the same rules as an adopted sheet.
- tests/styles.test.ts.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
