The following CSS reference guide highlights the major styles used in MOSS and WSS v3 sites. The guide is organized by area of the page and include the style name, function, CSS file name and approximate line number and a sample screenshot of the style location on the screen. Additionally, there is a "Copy to Clipboard" function that will copy the source code for the style to your client machine's clipboard for use in your own CSS file. Use these guides to identify styles that can be overridden for your custom branding and installation or to quickly reference style name and CSS information for customization. Note, Copy to Clipboard ONLY WORKS in INTERNET EXPLORER. This functionality will not work in Firefox due to restrictions with the Firefox browser itself.
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-usNeed to Learn More About CSS?Check out this article first: SharePoint and Cascading Style Sheets: How to update, change and reference
HeatherSolomon.com - SharePoint 2007 CSS Reference Chart