The keyboard navigation is useless. It used to work just as well as navigation by mouse until this version. Now I have to watch to not touch the keyboard because it usually navigates somewhere totally unpredictable, which then causes considerable time to be wasted to locate the place I was at when I touched some of the simplest navigation keys, like up- and down-arrow, page-up and down, blank. Up- and down-arrows used to perform the same as the mouse-wheel forward- and backward-rotation albeit with slightly different step. Now I need to first click on the uppermost visible text line for upward scrolling or the lowest visible line for downward scrolling before I can scroll with up- and down-arrow keys. The clicking action makes visible a vertical bar similar to what one has in most text editors. Placing it anywhere else in the visible text lines disables any scrolling until this editorial bar reaches the limit in respective direction. If that bar is scrolled off the window by scroll-up or -down mouse action the up- and down-arrow keys do something confusing, probably or possibly reverting to the last up- or down-arrow key-managed position but at the wrong end of the window, so that one needs to scroll 50-60 lines in correct direction in order to start scrolling OR place the vertical bar manually before using the functionality of up- and down-arrow keys. Blank key has a similar effect of taking my text to an unwanted position but I can't be more precise. It's plain confusing. Page-up and down keys are similarly confusing. Pressing page-down scrolls not 1 page down but all the way down to the last line on the page. Page-up then only toggles a pageful up or down from the bottom. I don't think you need any technical details of the keyboard used - it's the same one I used some years now. What changed is the Firefox version - I accepted to update to 57. I'm glad I can be of any help to make your product better.