I think I'm fine with the (pseudo)underline for h2, but the under/overlining of h5 makes it stand out more than h3-4.
It works for me, and the only page I know of with H5 and H6 headings is the Game Courier Developer's Guide, which I wrote anyway. If I'm to do away with the lines, I need an alternative that works as well, and I don't have one. I did try small-caps for H5 and small-caps plus italics for H6, but italicized small-caps differs from small-caps merely by being slanted. So, I chose not to do it that way.
Since you pointed out wikipedia's, note that h4-h6 are all the same, and h3 only differs from those in font-size.
Yes, I'm not a fan of how Wikipedia is styled. I borrowed one idea from Wikipedia, because it seems to work, but I don't like how some of their headings differ only by size. It makes it harder to tell what level something is.
It works for me, and the only page I know of with H5 and H6 headings is the Game Courier Developer's Guide, which I wrote anyway. If I'm to do away with the lines, I need an alternative that works as well, and I don't have one. I did try small-caps for H5 and small-caps plus italics for H6, but italicized small-caps differs from small-caps merely by being slanted. So, I chose not to do it that way.
Yes, I'm not a fan of how Wikipedia is styled. I borrowed one idea from Wikipedia, because it seems to work, but I don't like how some of their headings differ only by size. It makes it harder to tell what level something is.