The page looks better at about 950px and above... that sidebar doesn't help.

Looks like it renders correctly at 50% zoom.

I think it may have something to do with display:flex. CSS isn't a strength of mine but looking at the computed view, there's a wide inflexible margin on the right side that causes the text to wrap before it otherwise would need to on smaller screen widths. The nav causes the same on the left side.