问题描述
！ in CSS是什么意思？
它是用于css2，css3，IE吗？
What does !important in CSS mean?
Is it for css2, css3, IE only?
推荐答案
这意味着，
在正常使用中，定义的规则是：外部样式表被在文档的头中定义的样式所覆盖，而该样式又被元素本身内的内联样式推翻（假设等式的选择器）。使用！important 'attribute'（？）定义一个规则会丢弃关于'later'规则覆盖'较早'规则的正常问题。
In normal use a rule defined in an external stylesheet is overruled by a style defined in the head of the document, which, in turn, is overruled by an in-line style within the element itself (assuming equal specificity of the selectors). Defining a rule with the !important 'attribute' (?) discards the normal concerns as regards the 'later' rule overriding the 'earlier' ones.
此外，通常，更具体的规则将覆盖较少特定的规则。所以：
Also, ordinarily, a more specific rule will override a less-specific rule. So:
a {
/* css */
}
通常被推翻：
body div #elementID ul li a {
/* css */
}
由于后面的选择器更具体（并且通常不会发生更具体的选择器 head 或外部样式表）将会仍然覆盖较少特定的选择器（内嵌样式属性将始终 >重写more-或less-特定选择器，因为它总是更具体。
As the latter selector is more specific (and it doesn't, normally, matter where the more-specific selector is found (in the head or the external stylesheet) it will still override the less-specific selector (in-line style attributes will always override the 'more-', or the 'less-', specific selector as it's always more specific.
但是，将！important 添加到less特定选择器的CSS声明中，它将具有优先权。
If, however, you add !important to the less-specific selector's CSS declaration, it will have priority.
使用！important 有它的目的（虽然我很难想到他们），但它很像使用核爆炸阻止狐狸杀死你的鸡;是的，狐狸会被杀死，但鸡也是如此。
Using !important has its purposes (though I struggle to think of them), but it's much like using a nuclear explosion to stop the foxes killing your chickens; yes, the foxes will be killed, but so will the chickens. And the neighbourhood.
这也使你的CSS调试成为噩梦（从个人，经验和经验）。
It also makes debugging your CSS a nightmare (from personal, empirical, experience).
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