I don't blame you. UI design is difficult.
Yeah, this isn't your fault. There's this resurgence in the idea that once-size-fits-all. It never worked well in the past, and it still doesn't. It's usually the desktop users who suffer most while the interface is 'dummbed-down' for the mobile users. Knowing now that's what you've done, you've actually done a far better job than most. So in spite of my not liking certain things about the redesign, I have to say good job.
That's non-standard UI and it's not intuitive, however, now that I know how it works, it will come in handy. Thanks.
I did some debugging and discovered what the issue is. It's not browser specific since it happens to me on Safari as well. The problem isn't because I have a small screen, it's because I have a larger screen and dont run things full screen, or even in large windows. I blew my browser to full-screen and discovered that you have another very large (2" tall) 3rd header that's hidden from me when I have my browser in my normal-size.
Slowly rezise your browser, making it smaller until that header (the one with the juicy ass) disappears. Now, try to duplicate this behavior that three of us have reported up here. Open a page and slowly scroll down, and you should experience the issue. Personally, I think I'd rather have that keep happening than have that other huge header showing up on each page. Anyway, that's what I've found.