However, there are many confusing things to me as a person who arrived at the site through HN. Since one of the developers is promoting the "app" here, it might be useful to hear from him on these points:
1. Is this an input format or is it a publication format, or is it a viewer? Does it rely on a time-tested plaintext markup format like LaTeX or markdown? Perhaps it is a HTML viewer for a LaTeX markup document with special structure, rather than an actual typset web publication format.
2. What is the conceptual structure of the document system? Giving me a screenshot does not show me anything about the way you are conceptualizing your document. Is there a separation of content and output, output and viewer?
3. Is any part of this open source? Are you incorporating any other major technologies which have already been developed?
I apologize if any of the above seems harsh, but this is an important topic and I have become slightly tired of seeing flashy presentations about poorly-thought out "revolutionary" new document formats/tools/whatnot.