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).

src/card-controller/types.ts

@@ -134,7 +134,6 @@ export interface CardElementAPI {
   getMediaLoadedInfoManager(): MediaLoadedInfoManager;
   getMediaPlayerManager(): MediaPlayerManager;
   getMicrophoneManager(): MicrophoneManager;
-  getStyleManager(): StyleManager;
   getQueryStringManager(): QueryStringManager;
 }