The name of the city, as shown on the map, is Montreal
D3 knows to put the map into the content section of the HTML, because of the #contents ID selector in line 6 of the displayed code. This line also communicates with the CSS through the #contents ID.
The 90 value is an x axis value which rotates the earth on its axis to show different longitude values in the map extent. The second value refers to latitude extent and will change the view to face closer to either pole. The Americas are located at the 90 x value.
Within the style.CSS document, we would need to add another class selector under the #contents ID. It may look something like this: