Monospaced font for google groups messages

I found this userstyle to solve my initial problem, I wanted to use Andale Mono and change the kerning, so here is my diff:

var css = "@namespace url(http://www.w3.org/1999/xhtml); #inbdy, #cmp_body { font-family: AndaleMono !important; font-size: 10pt !important; letter-spacing: -0.1em}";