This is specifically about how jquery mobile works differently in web pages in in web apps.
If this example template below is opened in S40 web browser jquery mobile styles are applied as expected.
http://tinyurl.com/bwuz5f8 (short link)
If this same exact page is packaged as a web app, jquery mobile styling doesn't work at all.
http://goo.gl/mc1Y8?type=webapp (link to web app)