::before ::after什么意思?

RT, html代码里出现这个::after,  这是什么意思呢? 用来干嘛的?

NadiaSmile
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微积分2016

::before,::after 伪元素 :before,:after 伪类

慕田峪6141110

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qq_小盛开_0

伪类,为某个元素前后添加内容

心有猛虎_细嗅蔷薇

http://www.imooc.com/code/4409《十天精通CSS3》课程里有详细的介绍^_^

GTX760

伪类,就是before、after。也就是前和后加一个类
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