Your last paragraph basically says "remove the biggest flaws with Metafilter's design compared to HN's - and then they are pretty much the same". ;) I won't go

Your last paragraph basically says "remove the biggest flaws with Metafilter's design compared to HN's - and then they are pretty much the same". ;) I won't go into the color scheme since I guess that is a matter of taste, but at the same time I don't think it's an accident that you don't see the same color combinations used anywhere else ;) The comment nesting and placement of the comment credit line(s) is actually really important. It is vital to make the different comments easy to visually separate from each other. HN has one line above and one line below each comment, effectively boxing them in. That, plus the comment nesting, makes HN's comment threads easy to read and skim over. Metafilter on the other hand has just one line below each comment. Unlike on HN, where the line has a lower contrast/eye focus than the comment text, the line on MF is using the same colors as the links in comments. That is completely counter-productive, and objectively bad design. Since MF doesn't have comment nesting it should do something else to visually separate the comments. Most other sites subtly change the background color, but there are also other ways to do it. High contrast/big size should be used for things that should be focused on, and small contrast/small size for things that shouldn't be focused on. On HN the contrast between the color and size of the objects mostly make sense (although self posts should have darker text), but on MF it is all over the place.