User blog comment:Rupert Giles/Layout Changes: Breakpoints and Typography/@comment-4189499-20150520014724/@comment-4189499-20150520040759

At tablet portrait width, which is whatever width is reached once the right sidebar goes away as far as I care, the content width should expand to fit the full screen width. It just looks weird with empty bars down the side, making an already skinny view even skinnier, especially as the content space is then smaller than it was for tablet landscape mode so it can definitely go bigger and be within the content width bounds. Note that I am looking at tablet width when turning my Surface sideways so it's 1440px wide. Note also that according to the table in the blog, that should be desktop width, but the page is correctly showing tablet portrait while I'm using my computer as a tablet in portrait mode with the background image gone and the right sidebar down the bottom, again enforcing that the chosen display is not based upon pixel widths.