Add another container around the player to move back toward multi-player support.

static/clicks.css

@@ -277,7 +277,7 @@
   font-family: "source-code-pro";
 }
 
-.clicks-player-container {
+.clicks-players-container {
   position: absolute;
   -webkit-user-select: none;
   -moz-user-select: none;
@@ -286,14 +286,18 @@
   left: 0;
   right: 0;
   bottom: 0;
-#  TODO(flamingcow): How do we center this?
-#  display: flex;
-#  align-items: center;
-#  justify-content: center;
-  overflow: scroll;
   background-color: black;
 }
 
+.clicks-player-container {
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  overflow: scroll;
+}
+
 .clicks-player-crop {
 }
 

static/clicks.js

@@ -374,8 +374,10 @@ Clicks.prototype.buildUI_ = function() {
     }
   }
 
+  this.playersContainer_ = this.createElementAndAppend_(
+      'clicks-players-container', this.container_);
   var playerContainer = this.createElementAndAppend_(
-      'clicks-player-container', this.container_);
+      'clicks-player-container', this.playersContainer_);
   this.playerCrop_ = this.createElementAndAppend_(
       'clicks-player-crop', playerContainer);
   this.playerScale_ = this.createElementAndAppend_(