Refactor: CSS handling (#2344)

* refactor(css): only load base styles, add css task, cleanup exports
* style(base): add edge label bg
* refactor(css): use css-utils
* feat(core): add Panel component
* refactor(background): cleanup
* refactor(css-handling): cleanup

packages/background/src/index.tsx

@@ -1,2 +1,2 @@
-export { default as Background, default } from './Background';
+export { default as Background } from './Background';
 export * from './types';