Hmm ... that's not encouraging. It's possible some little tweak on the site caused the change, or some little update to your phone's software. Honestly, there's so many combinations out there and corner cases for all the bits and pieces in the software chain ....
Unless the site maintainers are able to recognize the issue and fix it, my only real advice at this point is to at least try the new Responsive_Blue theme. It's supposed to be more mobile device friendly and might display a bit better on your phone. Worth a try.
Of course you could always try another web browser, but for most people that's fairly disruptive.