code: function () {
      if(this.isHidden()) return;
  
      var
      offset          = this.model.get("offset"),
      pos             = this.mapView.latLonToPixel(this.model.get("latlng")),
      x               = this.$el.position().left,
      y               = this.$el.position().top,
      containerHeight = this.$el.outerHeight(true),
      containerWidth  = this.$el.width(),
      left            = pos.x - offset[0],
      size            = this.mapView.getSize(),
      bottom          = -1*(pos.y - offset[1] - size.y);
  
      this.$el.css({ bottom: bottom, left: left });
    }
docs: Update the position (private)