I don't think I'd use that demo. It found me in another
city!
And, alas, that is the problem if you expect it to work on
desktop. Do you?
I doubt you will find an easy "theme" that you can just
drop in. You will have to put on your thinking cap and dig in!
We seem to get a lot of traffic here from people who have gotten
some "theme" and then want to make some change to it. The
sad truth is, "themes" tend to be useful only when what you
want to do is EXACTLY what the theme does. And most are badly-written. :(
(When I say "theme", I do not mean jQuery Mobile CSS
theme, which is just some CSS for restyling JQM widgets. I mean
pre-packaged example websites that many people sell or give away, and
give many non-developers false hope that they can just drop it into
their website... They will usually work... if you find a good one...
and if all you need to change are the words!)
I suggest using jquery.ui.map:
It makes a lot of things easier vs. using Google Maps API directly.
While it's made for jQuery UI, it works with jQuery Mobile! Pay
attention to the specifics in the documentation about jQuery Mobile,
and search here and StackOverflow, etc. for tips.
A caution, though, it looks like jQuery UI map might be
"abandonware". I haven't used it lately myself, so
haven't kept track to see if somebody else has taken over the
project or forked it and actively maintaining it. Otherwise, ongoing
changes by Google will eventually make it obsolete. Perhaps current
users can comment.