Web Programming with HTML5, CSS, and JavaScript

3.9 Cascading

Have you wondered about the significance of the words in “Cascading Style Sheets”? Traditionally, a “style sheet” is a collection of rules that assign appearance properties to structural elements in a document. For a web page, a style sheet “rule” refers to a value assigned to a particular display property of a particular HTML element. The “cascading” part of Cascading Style Sheets is the subject of this section. If you look up the word “cascade” online or in a dictionary,² you’ll see something like “a series of stages in a process.” Likewise, CSS uses a series of stages. More specifically, there are different stages/places where CSS rules can be defined. Each stage/place has its own set of rules, and each set of rules is referred ...