Refactor styles on video playback page

Made changes to the styles on the video playback page to enhance visibility and address issues with the video player.
Added a new custom style file for Plyr, and removed redundant and unused styles in watch.css.

Specific changes:
- Added custom_plyr.css for Plyr styles.
- Removed redundant styles related to playback issues in watch.css

youtube/templates/watch.html

@@ -8,14 +8,8 @@
     {% if settings.use_video_player == 2 %}
         <!-- plyr -->
         <link href="/youtube.com/static/modules/plyr/plyr.css" rel="stylesheet">
+        <link href="/youtube.com/static/modules/plyr/custom_plyr.css" rel="stylesheet">
         <!--/ plyr -->
-        <style>
-         /* Prevent this div from blocking right-click menu for video
-         e.g. Firefox playback speed options */
-         .plyr__poster {
-             display: none !important;
-         }
-        </style>
     {% endif %}
 {% endblock style %}