html, body { margin:0; padding:0; width:100%; height:100%; background:#000; }
#container { width:100%; height:100%; display:flex; align-items:center; justify-content:center; }
#container img,
#container video,
#container object,
#container iframe { max-width:100%; max-height:100%; }
video { background:#000; }

#container canvas {
  max-width: 100%;
  max-height: 100%;
  display: block;
  margin: auto;
}