I don't really play with iOS and don't actually have an iOS device to test it with, but one observation looking at the source code is the CSS. I know typically doing responsive webdesign like this, people will tend to use CSS media queries, but I've not made anything that changes based on the orientation, just the screen width. However, I suspect you'll be able to scale it based on a CSS media query, I don't know if it is worth experimenting with.
I don't know how familiar you are with using them, so I'll play it safe and will assume nowt, but don't know if it was intentional or not, so here's a link to some more info on them:
http://www.w3schools.com/cssref/css3_pr_mediaquery.asp
But the idea is you can use different CSS rulings, based on the width of the screen. But I don't know how much the style is affected by your JavaScript, I'll admit I just had a very quick glance through.
I don't know if the "screen width" value ever changes based on orientation and imagine it would, I feel like it should, but haven't actually tested it.