css 权威指南文摘

对css不是很熟，开始看css权威指南，摘录其中一些对自己比较有用的片断。

3.2 Inheritance
As important as specificity may be to understanding how declarations are applied to a document, another key concept is inheritance. Inheritance is the mechanism by which styles are applied not only to a specified element, but also to its descendants. If a color is applied to an H1 element, for example, then that color is applied to all text in the h1, even the text enclosed within child elements of that h1:

h1 {color: gray;}

<h1>Meerkat <em>Central</em></h1>


12.2.1. Inserting Generated Content

To insert generated content into the document, use the :before and :after pseudo-elements. These place generated content before or after the content of an element by way of the content property (described in the next section).

For example, you might want to precede every hyperlink with the text "(link)" to mark them for printing. This is accomplished with a rule like the following, which has the effect shown in Figure 12-11:

a[href]:before {content: "(link)";}