remove redundant background color from player HTML

Author: sarbagyastha

packages/youtube_player_flutter/example/analysis_options.yaml

@@ -9,15 +9,13 @@
       html {
         width: 100%;
         height: 100%;
-        background-color: black;
         pointer-events: <<pointerEvents>>;
       }
 
       body {
         margin: 0;
         width: 100%;
         height: 100%;
-        background-color: black;
         pointer-events: inherit;
       }