I don't, because I have no problem with the way it really looks, and it's too much trouble to use one
I do use a small stylesheet for it, though, just to help with images
img {
max-width: 1000px;
}
img.avatar {
max-width: 75px;
}
the first bit gives images a max width of 1000 pixels, so there's no stretching
and that bit breaks the avatars some people used to use that were over 75x75. I'm not sure if anyone actually still uses those, but that's what the second one fixes either way