White triangle persists when not using Google infowindows

[Kirkman]

I have some maps where I am not using Mapsheet's popupTemplate (the default infowindow).

My code works well, but there is always a white triangle left over from Google's infowindows. You can see an example of one in the upper left corner of the map I attached. You can also experience it by looking at the link below. Just a click on any map marker:

http://www.stltoday.com/lifestyles/food-and-cooking/interactive-map-st-louis-area-farmers-markets-copy/html_adae6fe0-ee71-5ed0-b213-1b0f2179f7a9.html?6

How do I hide this triangle? Google's html code doesn't provide a class I can just block in CSS. Is there something that can be done on the Mapsheet side to fix it?