Font size parse error?

Hi,
I'm trying to validate some web pages I'm writing which in turn use CSS
based on some CSS from devedge.netscape.com (
http://devedge.netscape.com/viewsource/2003/devedge-redesign-css/
<http://devedge.netscape.com/viewsource/2003/devedge-redesign-css/> )
but I'm getting errors in the validate that don't understand.
 
I get the following parse error (via the validate uri service)  on html
pages where the style sheet link specifies  media="all"   but not on the
ones that specify media="screen,projection":
 
  Line: 1 Context : body 
  Invalid number :  font
<http://www.w3.org/TR/REC-CSS2/fonts.html#propdef-font> Parse Error -
[empty string] 
 
One of the offending lines looks like:
   body {background: white; color: black; font: 12px Verdana,
sans-serif;
    margin: 0; padding: 0.5em; border-width: 0;
    min-width: 55em !important; position: relative;}
I think the error is related to 12px (it being the only number on line
1). Is there a problem with the validator or can't I specify font size
using px when media type= "all" ?
The devedge pages have the same issues. Here's one that validates (uses
media type = "all"):
http://devedge.netscape.com/ <http://devedge.netscape.com/> 
and one that doesn't (uses media type = "screen,projection" )
http://devedge.netscape.com/viewsource/2003/junkmail-filtering/
<http://devedge.netscape.com/viewsource/2003/junkmail-filtering/> 
Thanks for any help, and I apologise if this isn't a bug with the
validator but due instead to bugs in my understanding of CSS.
 
Regards,
Paul