Here is the CSS reference link that can be used in the Moss 2007 and WSS 3.0.
The default CSS files are located on the web server in the following directory: Local Drive:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS\1033\STYLES.
Additional styles are located in the Publishing feature: Local Drive:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\FEATURES\PublishingLayouts\en-us
