In my opinion, that’s a bigger problem than CORS. Proxyless web feed reader is a lost cause, you’re wasting your time because only a small minority are ever going to support it. But that opacity and transition nonsense gratuitously slows down page loading for everyone, and hides content completely for those that aren’t running JS.

(What I would also like to know is: how come this is the third time I’ve seen exactly this—each block of content having this exact style attribute—in the past month, when I don’t remember encountering exactly it before?)