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

babel.config.js

@@ -4,5 +4,4 @@ module.exports = {
     '@babel/preset-typescript',
     '@babel/preset-env',
   ],
-  plugins: ['./tooling/inject-css-babel-plugin'],
 };