body {
  background-color:black;
}
canvas {
background:url("http://www.lacor.info/gnrl/codepen/img/eiffel_tower.gif") no-repeat ;
background-size:auto 100%;
background-position:50%;
  z-index:1;
  display:block;
  top:0;
  left:0;
  position:absolute;
}