suite/themes/modern/communicator/fullscreen-video.css

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

html,
body,
video {
  height: 100%;
}

html {
  background-color: black;
}

body {
  margin: 0px;
  overflow: -moz-hidden-unscrollable;
  visibility: hidden;
}

video {
  width: 100%;
  max-height: 100%;
}

div {
  position: absolute;
  top: 0px;
  right: 0px;
  width: 32px;
  height: 32px;
  background: url("chrome://communicator/skin/icons/closeFullScreenVideo.png") center center no-repeat;
}