"CSS2.0 Programmer's Reference Manual" Chapter 1 CSS Basic Concepts

In order to understand how CSS affects the performance of a document, there are some key concepts that must be mastered. Once you understand these, even small parts of them, it will be easier to understand how properties and values ​​work in CSS. However, don't feel like you have to fully understand everything in this chapter before trying to use CSS. In fact, it is best to review the first chapter first, and then use the properties involved.