CSS <length> can be bare zero

Grant Husbands wrote a reply to the W3C Markup-Validator list 
<mailto:www-validator@w3.org> on 12 April 2005 in “Re: Margin attributes 
not accepted by XHTML 1.0 & impossible to validate   CSS” 
(<mid:425B9228.8010708@grant.x43.net>, 
<http://www.w3.org/mid/425B9228.8010708@grant.x43.net>):

>> You can use CSS to set the margins instead.
>>
>> body { margin-top: 0; margin-top: 0; }
> 
> 
> This is missing units and repeats margin-top. A corrected version:
> 
> body { margin-top: 0px; margin-left: 0px; }

In CSS, a <length> can be a bare zero with no units. This is according 
to section 4.3.2 of the CSS2.1 specification (“Lengths”, 
<http://www.w3.org/TR/CSS21/syndata.html#length-units>).

-- 
Etan Wexler.