CSS 选择器是做什么的？

最近我在 CSS中遇到了 * *。

网站参考资料 -网站连结。

对于 CSS 样式表中的单个 *使用，Internet 和 Stack Overflow 充满了示例，但是我不确定在 CSS 中使用两个 * *符号。

我谷歌了它，但无法找到任何有关这方面的信息，作为一个单一的 *选择所有元素，但我不知道为什么该网站使用了两次。缺少的部分是什么，为什么使用这个黑客(如果它是一个黑客) ？

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* * Matches everything except the top-level element, e.g., html.

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最佳答案

Just like any other time you put two selectors one after another (for example li a), you get the descendant combinator. So * * is any element that is a descendant of any other element — in other words, any element that isn't the root element of the whole document.

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That selects all elements nested inside another element in much the same way div a would select all <a> elements nested somewhere inside a <div> element.

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* means apply given styles to all the elements.

* * means apply given styles to all the element's child elements. Example:

body > * {
margin: 0;
}

This applies margin styles to all the child elements of body. Same way,

* * {
margin: 0;
}

applies margin: 0 to *'s child elements. In short, it applies margin: 0 to almost every element.

Generally, one * is enough. There's no need for two * *.

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Just a little big example:

Try to add this on your site:

* { outline: 2px dotted red; }
* * { outline: 2px dotted green; }
* * * { outline: 2px dotted orange; }
* * * * { outline: 2px dotted blue; }
* * * * * { outline: 1px solid red; }
* * * * * * { outline: 1px solid green; }
* * * * * * * { outline: 1px solid orange; }
* * * * * * * * { outline: 1px solid blue; }

Demo: http://jsfiddle.net/l2aelba/sFSad/

Example 2:

Demo: http://jsfiddle.net/l2aelba/sFSad/34/