#Firefox #reading view
badly needs #columns
. At this moment, unfortunately, I can't even do a fine search to understand if there already any issue to add them.
On big screen it wastes half or more of space, especially if you use smaller font size. The reading experience and speed would be highly improved. It already limits width of the text for better reading, so making few columns just a next logical step. For example MS Word reading mode is mostly perfect for any size of the screen.