I have loved Reader for at least a year. Now, the last few days, there is no longer an icon in the address bar, and no choices for page color and font. Can't remember when FF last upgraded, currently 58.0.2. Very much missing the sepia tone + brown helvetica font.
( re icon: in the past, a small grey tile, like a page of text, sat in address bar. This was in addition to, or instead of, the orange R tile, which I have now brought back into my toolbar.) Even tried downloading Reader again, but no change.