Due to some odd interaction between the flexbox display of the map + postalcode form when it was embedded in the home page, there was a substantial pixel offset between a click event on the map and the pixel location that was reported by the event, making it hard to select a feature. I tracked it down to some CSS in the html.css file, and simply deleting it solved the problem. I also worked on the display of the map-only page, and reconfigured that so that the map takes up the bulk of the viewport and no space is wasted.