The HTML page is always displayed on top of the AR View. Since the Radar is part of this AR View it will always be displayed behind any HTML elements. Make sure you don't obstruct the area where the radar will appear. Use css properties like, "background: none" or transparent color values to hide any distracting html elements.
almost 10 years ago
I've created a simple GUI with html, div and images first thing in the body section. I then run the script that creates the AR world, radar, POIs etc. The radar shows up but is mostly hidden by the images/GUI I created. I also tried reversing the order - Running the <script> first, then creating the html GUI. Finally I tried setting a z-index of -5 to my GUI. No dice.