Hi, my name is Eugene Dovbush, I did such task for my own map project "Where to bring waste" in Kyiv and other cities. I customized the infowindow so that it is a div as you can see on this map: [login to view URL]
So I know how to do it for your map. I am a beginner on the freelancer.com website, but you can be sure in my competence. Please see my portfolio where I put links on my map projects.
We can discuss details of the task in a chat. Thank you.