Hello,
I'm a web developer lead and work closely in developing software architecture using leading technologies in the opensource world.
Here's my input on this project: since you already have the API and UI design, it'll be a matter of recreating the design in HTML and CSS and overlaying it over the PDF viewer. I can deliver on this project by leveraging my experience in Javascript and the many libraries around it.
Please provide me with some further details of the development environment and I can turn this project around quickly and with quality.
Thank you. KM.