You probably use a user agent different from the default one set in the stock browser. You may want to try changing it in the options of Opera, just to see whether this is what changed the display of Facebook (which I don't use, can't really help here).

I agree that it would be ideal if we could use the stock keyboard in Opera. I like the Opera keyboard, but it's easier to familiarize with only one keyboard rather than two, so the stock one wins. Swype users have arguments too. I actually do less typos mistakes with the Opera keyboard I think, but practicing the N9 one in other applications may change this in a near future, and I really (REALLY) miss the tactile feedback on the Opera keyboard. Any way to add this feature?