Does the CSS direct decendant (>) not have any value in selectivity?

问题

Given the following class declarations and code...

.foo > a { color:green; }
.bar a { color:red; }

<div class="bar">
    <div class="foo">
        <a href="#">SOME LINK</a>
    </div>
</div>

... I thought that the link would be green because, while both declarations have a class (010) and an element (001), .foo has the direct descendant selector. But alas, the link is red. Why?

回答1:

There's no value for > for css specificity.

Both case have 11 value for specificity:

.foo > a { color:green; }/*specificity value is 11*/
.bar a { color:red; }/*specificity value is 11*/

In your case you may use like this to have greater specificty:

.bar .foo > a { color:green; }/*greater specificity value is 21*/
.foo a { color:red; }/*specificity value is 11*/

Ok, I'm going add here how specificity works:

Selector                          Specificity         Specificity in large base
inline-style                      1 0 0 0             1000
id selector                       0 1 0 0              100
class,pseudo,attribute selector   0 0 1 0               10
type selector and pseudo elements 0 0 0 1                1

回答2:

You have two conflicting CSS rules. Direct descendant selector has the same specificity as descendant selector if I am not mistaken, therefore the rule parsed later will override the formerly parsed rule, so if your rules are:

.foo > a { color:green; }
.bar a { color:red; }

then the color will be red. If your rules are:

.bar a { color:red; }
.foo > a { color:green; }

then the color will be green for any anchors which fulfill the selector of both rules.

回答3:

Combinators don't have any value in specificity only selectors have :id, class, tags , pseudo elements , pseudo classes, attribute selectors.

来源：https://stackoverflow.com/questions/27203293/does-the-css-direct-decendant-not-have-any-value-in-selectivity

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css

html5

css3

css-selectors