What's wrong with my CSS?

Geek Speak

My <pre> styling looks OK (to me at least) in IE 6 and horrible (double spaced and strange) in Firefox. Can anyone tell me why?

The CSS looks like this:

pre {
   color : #990000;
   font :  "Courier New", Courier, monospace;
   font-size:small;
   font-weight:normal;
   padding : 5px;
   line-height:100%;
}