Sometimes I think I want to develop a standalone (needing neither a web server nor a browser to run) desktop GUI application for Windows, Mac OS X and Linux using HTML5, CSS and JavaScript to form the GUI.
But as far as I know, both Adobe AIR and Mozilla Prism are deprecated. What are other options for this task?
UPDATE: Responding to the answers and comments already got, I'd like to emphasize that the applications must work on Windows, Mac OS X and Linux without any serious modifications. The platform is to be actively developed and supported for all the 3 major PC OSes. Single-platform applications are not an option, neither are applications with limited support of one of them.