fix: Improve media background image (#1635)

* fix: Improve media background image

* Simplify loading spinner.

This is slightly less fancy, but removes code. I'm guessing no-one will notice or care enough to raise it! (BMFW).

tests/card-controller/card-element-manager.test.ts

@@ -127,7 +127,6 @@ describe('CardElementManager', () => {
     expect(api.getExpandManager().initialize).toBeCalled();
     expect(api.getMediaLoadedInfoManager().initialize).toBeCalled();
     expect(api.getMicrophoneManager().initialize).toBeCalled();
-    expect(api.getStyleManager().initialize).toBeCalled();
   });
 
   it('should disconnect', () => {