As you known, some CSS styles are used very frequently. For example, display:none - the most commonly used method for hiding elements, visibility:hidden - a very useful method for hiding elements, and so on. Actually, zxx.lib.css is a collection of these styles. It includes display, margin, padding, color(web safe color), font refer, vertical-align, float, ..., and many other common styles. In addition to these styles, some group styles that I think useful are also in.