Desktop app, website, and mobile app combo

I want to build an app that shows different as a website vs. mobile app vs. desktop app. I understand how to create each of these, but do I need to make a version of each of the three seapartely or can I use one website and have that converted into each of the three?

Bumping this to the top as I have the same question.

I see rarely anybody in forum replies to this question!!
Many others too have asked how to use one single app for both desktop, mobile and website.

Is it even possible to do and if so how??


It is possible to design your app using the new responsive engine.
Doing so, your app would respond to various resolution sizes.

I know how responsive works. However:

A combo of above 3 will have multiple pages. There will be pages only suited for desktop - not ideal to be responsive. Others customized only for phone.

How would you recommend pushing such an app to play store?