Thanks for your message.
Yes, the Windows Phone 8.1 browser is supposed to be supported.
We have a Lumia 520 with Windows Phone 8.0 here for testing, and it works well. We are going to test again with a Windows Phone 8.1 as soon as possible, and keep you updated. If there has been any regressions, we are going to fix them asap. (I guess you have already tried reloading the page).