https://www.google.com/maps/d/viewer?mid=1Z4oQoYugPPT2JH81FuZ_GrlrNGNwd9A
This is display.cgi (source). It takes some text you enter into a form, and displays it for you as HTML. This is a great way to see how some HTML code looks in your (or someone else's) browser. So paste 'n go: