Add map JSON for geojson template

If I create a basic map like:

map = folium.Map(location=center, zoom_start=zoom, width='100%', height='100%')
map.create_map(path="maps/test.html")

Things work fine.  If I then add geojson to the map:

map = folium.Map(location=center, zoom_start=zoom, width='100%', height='100%')
map.geo_json(geo_path=filename)
map.create_map(path="maps/test2.html")

I get a blank page.

It appears the difference is this bit of CSS, which is present in my first test.html file but not in test2.html:

#map {
  position:absolute;
  top:0;
  bottom:0;
  right:0;
  left:0;
}

Let me know if there's a cleaner way to fix this, or if I'm way off base!