When working on this, please also consider this example: Visit
Scroll down to the map near the bottom of the map. Using a two finger spread, you can zoom in on the map. (You may prefer to remove the legend menu using its close box first.) And in the other direction, you can zoom out using the two finger pinch. But if you take it too far, you activate the Tab View Sidebar or Grid, which is not desirable at this point.