CSS content property not displaying

I am new to CSS and I'm following a book example:

Iv'e copied the following from the book and saved it as HTML. all the css properties seem to work except the "content" property which does not display.Thanks in advance.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
    <head>
        <title> The content property </title>
        <style type='text/css' media='all'>
            div {
                content: "Hello, world!";
            }
        </style>
    </head>
    <body>
        <div></div>
    </body>
</html>

CSS content property not displaying

3 Answers