Formatting problems are making it start out pretty much unreadable for me on Firefox on Mac [1]. Whatever is laying out the text and sidebar is using a width that is much larger than the width of the white area, so part of the text and all of the sidebar end up out in the black right margin. Since the text is black, this doesn't work well.

Workaround: narrow the width of the white area. As soon as the window shrinks to that width, it changes to a format that appears to be designed for narrow devices.

The narrow layout correctly matches the width of the text display to the width of the white area.

[1] 58b014