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

.yarnrc.yml

@@ -1 +1,5 @@
 nodeLinker: node-modules
+
+plugins:
+  - path: .yarn/plugins/@yarnpkg/plugin-workspace-tools.cjs
+    spec: "@yarnpkg/plugin-workspace-tools"