Portrait mode collapses x-axis on vega-lite chart on Mobile

the second chart on https://observablehq.com/@dmaynard/covid-19-us-states-explorer collapses the x axis into one pixel in portrait mode in both Chrome and Safari on my iPhone 7. If I rotate the phone to landscape mode it renders properly.

Any suggestions? Is this a perhaps a vega-lite issue? The same problem does not occur on the first chart on the page even though the chart and the data are very similar to the second chart.

This morning it seems to be working. Very strange.