!important 在 CSS 中是什么意思? [英] What does !important mean in CSS?

问题描述

!important 在 CSS 中是什么意思?

What does !important mean in CSS?

它在 CSS 2 中可用吗?CSS 3?

Is it available in CSS 2? CSS 3?

哪里支持?所有现代浏览器?

Where is it supported? All modern browsers?

推荐答案

本质上，它意味着什么；'这很重要，忽略后续规则和任何常见的特殊性问题，应用这个规则！'

It means, essentially, what it says; that 'this is important, ignore subsequent rules, and any usual specificity issues, apply this rule!'

在正常使用中，外部样式表中定义的规则会被文档head 中定义的样式覆盖，而该样式又会被元素本身内的内嵌样式覆盖(假设选择器具有相同的特异性).使用 !important 'attribute' (?) 定义规则会丢弃关于覆盖较早"规则的稍后"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不太具体的规则.所以:

Also, ordinarily, a more specific rule will override a less-specific rule. So:

a {
    /* css */
}

通常被以下因素否决:

body div #elementID ul li a {
    /* css */
}

由于后一个选择器更具体(通常，在何处找到更具体的选择器(在 head 或外部样式表中)并不重要，它仍然 覆盖非特定选择器(内嵌样式属性将总是覆盖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，如果您将 !important 添加到不太具体的选择器的 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 有其目的(虽然我很难想到它们)，但这很像使用核爆炸来阻止狐狸杀死你的鸡；是的，狐狸会被杀死，但鸡也会被杀死.还有附近.

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.

它还使调试 CSS 成为一场噩梦(来自个人、经验、经验).

It also makes debugging your CSS a nightmare (from personal, empirical, experience).

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