Seems to fall apart at smaller widths, as well as very large widths.
You’d probably need some media queries at larger resolutions to sort things out and make sure text isn’t too long. I’ll typically make content have a
max-width: 40em; so no matter what things won’t get too difficult to read.
Also, you should make your defaults OK on mobile. Less padding on the left and right, maybe bring the profile bubble down to the bottom (or top) to make more room for the content itself.