CSS初学者不知道使用子选择器是影响他们效率的原因之一。子选择器可以帮助你节约大量的class定义。我们来看下面这段代码：

<div id=subnav>

<ul>

<li class=subnavitem> <a href=# class=subnavitem>Item 1</a></li>>

<li class=subnavitemselected> <a href=# class=subnavitemselected> Item 1</a> </li>

<li class=subnavitem> <a href=# class=subnavitem> Item 1</a> </li>

</ul>

</div>

这段代码的CSS定义是：

div#subnav ul { /* Some styling */ }

div#subnav ul li.subnavitem { /* Some styling */ }

div#subnav ul li.subnavitem a.subnavitem { /* Some styling */ }

div#subnav ul li.subnavitemselected { /* Some styling */ }

div#subnav ul li.subnavitemselected a.subnavitemselected { /* Some styling */ }

你可以用下面的方法替代上面的代码

<ul id=subnav>

<li> <a href=#> Item 1</a> </li>

<li class=sel> <a href=#> Item 1</a> </li>

<li> <a href=#> Item 1</a> </li>

</ul>

样式定义是：

#subnav { /* Some styling */ }

#subnav li { /* Some styling */ }

#subnav a { /* Some styling */ }

#subnav .sel { /* Some styling */ }

#subnav .sel a { /* Some styling */ }

用子选择器可以使你的代码和CSS更加简洁、更加容易阅读。

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