Validation error messages from Lisa on 2004-07-20 (www-validator-css@w3.org from July 2004)

From: Lisa <yoyo@nicelytoasted.net>
Date: Tue, 20 Jul 2004 17:59:24 +0100
To: "www-validator-css@w3.org" <www-validator-css@w3.org>
Message-Id: <E1BmxvN-0000ly-00@mrelayng.kundenserver.de>

I'm having a little trouble understanding the meaning of one of my validation errors: 

Invalid number : background-positiononly 0 can be a length. You must put an unit after your number : 150 190

Can someone point me to an explanation of the error messages, please?

Received on Tuesday, 20 July 2004 12:57:17 UTC