I used Google Maps in my website with multiple markers and multiple infowindows. Somehow the the close buttons (the little x) stays hidden inside the infowindow, but works if cl
Depending of your custom css you may have also to add max-height: none.
img[src*="gstatic.com/"], img[src*="googleapis.com/"] { max-width: none !important; max-height: none !important; }