Don't constrain the size of the cue root

Source/core/css/mediaControls.css

 /*
  * Copyright (C) 2009 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 111 matching lines @@
 }
 
 video::-webkit-media-controls-overlay-enclosure {
     display: flex;
     position: relative;
     flex-direction: column;
     justify-content: flex-end;
     align-items: center;
     flex: 1 1;
     width: 100%;
-    max-width: 800px;
     text-indent: 0;
     box-sizing: border-box;
     overflow: hidden;
 }
 
 video::-webkit-media-controls-overlay-play-button {
     -webkit-appearance: media-overlay-play-button;
     display: flex;
     position: absolute;
     top: 50%;
@@ skipping 269 matching lines @@
     font-weight: bold;
 }
 
 video::-webkit-media-text-track-container u {
     text-decoration: underline;
 }
 
 video::-webkit-media-text-track-container i {
     font-style: italic;
 }