* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

#container {
  position: relative;
  width: 100vw;
  height: 100vh;
  overflow: hidden;
  background: url('https://upload.wikimedia.org/wikipedia/commons/8/80/World_map_-_low_resolution.svg')
              center center no-repeat;
  background-size: contain;
}

canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

#fireCanvas  { z-index: 1; }
#iceCanvas   { z-index: 2; }
#blendCanvas { z-index: 3; mix-blend-mode: normal; }