body { margin: 0; padding: 0; }
  #map { position: absolute; top: 0; bottom: 0; width: 100%; }
  .map-overlay{
    position: absolute;
    left: 0;
    padding: 10px;
}
.marker-blue {
  background-image: url('images/blue.png');
  background-size: cover;
  width: 25px;
  height: 25px;
  border-radius: 50%;
  cursor: pointer;
}
.marker-red {
  background-image: url('images/red.png');
  background-size: cover;
  width: 25px;
  height: 25px;
  border-radius: 50%;
  cursor: pointer;
}