Z-index obrázek a canvas

<div class="loader">
  <img src="map.png" class="bottom">
  <canvas class="top" width="128" height="128"></canvas>
</div>

div.loader {
  width:128px;
  height:128px;
  margin-left:auto;
  margin-right:auto;
  border:1px solid black;

}
div.loader img.bottom {
  position:absolute;
  z-index:1;
}
div.loader img.top {
  position:absolute;
  z-index:20;
}