I want to add a custom HTML element (that can become transparent dynamically) instead of a marker. 

Basically my html object would be a cirle (or rounded pin) with a picture of users in the middle.

I have imagined different solutions:

* place a label (containing HTML) covering the marker which visibility would be set to none
* work with overlays
* hard way: replace the marker with a PNG image that I should compose dynamically with some sort of library superimposing two images (one geometric and the other user picture).

Anyway I can't figure out what to do and how to do it.

Thanks,
Stefano