Mobile Browser Web Page Solution

I have a requirement to create a web page that is compatible on all mobile web browsers but I'm completely stuck on the design of the solution.

I have been tasked with building a single web page that users complete and then at the bottom of the page, are given the option to save a draft (to return at a later date and complete) or mark the form as complete (which finalises the process). The form is just a standard HTML form with form elements such as text boxes, buttons and drop down lists. There is no ajax, advanced CSS or jquery etc. Sounds simple right?

The two major constraints which are making this difficult are:

1/ After the web page is loaded, the user must be able to complete the form disconnected from any internet connection and then move into an internet zone, reconnect and save the form.

2/ On clicking certain buttons, a popup must appear and the开发者_开发百科y cannot return to the parent page until they click cancel or save.

How can I handle popups when for example the iphone launches them in a seperate screen?

How can I create a DIV popup when I cant use AJAX to get the rendered HTML, or use javascript to manipulate the DIV when it might not be supported?

Since the page is going to be used by mobile and desktop users I'm generating the form in XML and using XSLT to transform depending on the viewing platform. I thought I could then hold the original XML Document in a javascript global variable and any changing, deleting or adding to the form elements I could use js to update the XML Document, which would then be posted to the server on save. But not all mobile browsers support javascript.

This is my first ever mobile project so I'm really stuck on this one. Soo .... calling all IT professionals, if anyone could help me with this and point me in the right direction I would be eternally grateful!

Thanks in advance.

Just on this part:

On clicking certain buttons, a popup must appear and they cannot return to the parent page until they click cancel or save

That sounds like a good use case for the JavaScript confirm method, if the content of the popup can be just text. Are you not allowed to use JavaScript for some reason? (Lack of support on mobile browsers?)