How to move from website development to application development?

Question

Mobile development

There is a team of designer, coder, php programmer, they made websites for the company. We are doing well with the sites, but now we have received a task to make an application (a content application with articles and registration to gain access to the closed part, when registering, the user must send us his phone number - later the manager will contact him by phone).
The question is where to start, in what resolutions to make the layout (or maybe 1-2 of the most popular and adaptive is possible for others) What to do with the finished design (do I need to typeset in html + css or applications are not about it)
If there are experienced developers, tell me sequencing

Answer 1

apache cordova - make it look like a site on html + js, but it will be a mobile application. It fits exactly the task you describe.
Because in apache cordova there will be some kind of site (of course, this is not very correct in the definition, but the essence is clear), then you need to try to make it responsive, you can pull some bootstrap.