CSS: The Definitive Guide
Provides you with a comprehensive guide to CSS implementation, along with a thorough review of all aspects of CSS 2.1. Updated to cover Internet Explorer 7, Microsoft's vastly improved browser, this new edition includes content on positioning, text wrapping (nowrap), lists and generated content, table layout, user interface, paged media, and more.
from firefox2 -moz-opacity specification is not necessary, because w3c standard opacity is supported.