Would it be possible to inject a separate CSS stylesheet in to the HTML from your app? If you can do that, then you would be able to restyle a bunch of things using CSS.
Though if you're a c++ programmer it might be easier for you to do this in your native language by injecting something like:
<link rel="stylesheet" type="text/css" href="/path/to/mobile/optimized/styles.css">
Alternatively, the entire website might benefit from a mobile optimized stylesheet:
<link rel="stylesheet" type="text/css" href="/path/to/mobile/optimized/styles.css" media="handheld">
(Note the media attribute)
Of course for the latter option you would need to be able to place that stylesheet in to the <head> section of the website and make sure (most of?) the other stylesheets have an appropriate media attribute set. I realise that you probably don't have access, but thought I'd include it for completeness sakes