Here's just one more example why Emacs is so awesome
Reading mail in Gnus is very nice, but shr has become a little too good at its job. Add to this the many occasions when a background is specified without specifying a foreground, plus a color theme that is the inverse of what is usually expected, and you can get hard-to-read HTML messages, gray foreground and gray background.
I've looked at the other possible renderers, but they don't look very nice compared to shr. So just remove its ability to add background colors.