Okay, so the title sort of tells you why, but what I find irritating, is once I start scrolling, I have no idea where I am anymore (well unless I look at the address bar, but on a mobile that isn’t intuitive, as it hides).
Category Latest after scrolling:
I realize it is duplicating information, but once you scroll… I feel it is needed. Of course, the category button could be moved up to the header once scrolling begins. I’d accept that approach as well.