Haven't seen anything like this previously.
Why would you want users to move offline to view content? What would the use case be I wonder? And if the user moves offline, where is the content downloaded from?
Not sure if this plugin does what we are looking at here Offline Content — WordPress Plugins
Hi Preran, it is more a philosophical question. If you followed the website I mentioned, you will understand for sure.
It's not actually done off-line.
How it works is by storing the sites content, (text, videos and other content) in the database and in the off-line cache, then the page checks that there is no connection to the on-line site. If there is no connection the off-line content creates the actual site. Working in a very similar fashion to an actual device specific app, which is why if it was not for the easy method of being paid for an app, (apple/android store) the necessity of creating a device specific app would be unnecessay now, as everything that one can do with a device specific app, one can now do in a browser, (the users permissions are required to access the users contacts in a browser based version).