at some point recently, the header stopped scrolling in a way that lets you hide it on firefox. Now it's a permanent fixture at the top, reducing the space for the manga panel. It still scrolls on chrome.
Just to be sure, if you bring up/make visible the right sidebar(click in the middle of a page if you have it hidden to bring it up), there's a button labeled 'Header Hidden'/'Header Shown'. Does that not work?
