Chapter 19. Introduction to CSS

Using CSS (Cascading Style Sheets), you can apply styles to your web pages to make them look exactly how you want. This works because CSS is connected to the DOM (Document Object Model), which I explained in Chapter 14.

With CSS and its integration with the DOM, you can quickly and easily restyle any element. For example, if you don’t like the default look of the <h1>, <h2>, and other heading tags, you can assign new styles to override the default settings for the font family and size used, or whether bold or italics should be set, and many more properties too.

One way you can add styling to a web page is by inserting the required statements into the head of a web page between the <head> and </head> tags. So, to change the style of the <h1> tag, you might use the following code (I’ll explain the syntax later):

<style>
  h1 { color:red; font-size:3em; font-family:Arial; }
</style>

Within an HTML page this might look like Example 19-1 (see Figure 19-1), which, like all the examples in this chapter, uses the standard HTML5 DOCTYPE declaration.

Example 19-1. A simple HTML page
<!DOCTYPE html>
<html>
  <head>
    <title>Hello World</title>
    <style>
      h1 { color:red; font-size:3em; font-family:Arial; }
    </style>
  </head>
  <body>
    <h1>Hello there</h1>
  </body>
</html>
Styling a tag, with the original style shown in the inset
Figure 19-1. Styling a tag, with the original style shown in the inset

Importing a Style Sheet

When you wish to

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