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derived selector

Derived selectors allow you to style a tag based on the context of the document. By judiciously using derived selectors, we can make our HTML code cleaner. For example, if you want the strong element in the list to turn red instead of the usual black, you can define a derived selector like this: 

li strong{    color: red;
}

Please note that in the HTML it is marked <li>< ;strong> The context of the code

<p><strong>我是黑色，因為我不在列表當中，所以這個規(guī)則對我不起作用</strong></p>
        <u1>
            <li><strong>我是紅色。這是因為 strong 元素位于 li 元素內(nèi)。</li>
        </u1>

The complete code is as follows:

index.html

<!doctype html><html>
    <head>
        <meta charset="UTF-8">
        <title></title>
        <link rel="stylesheet" href="mycss.css" type="text/css">
    </head>
    <body>
        <p><strong>我是黑色，因為我不在列表當中，所以這個規(guī)則對我不起作用</strong></p>
        <u1>
            <li><strong>我是紅色，這是因為 strong 元素位于 li 元素內(nèi)。</strong></li>
        </u1>
    </body></html>

mycss.css

li strong{    color: red;
}

Running result:

QQ截圖20161011132215.png

##The style of li strong defined in css will only affect <li><strong> in the above html file, but will not affect <p>< Content in strong>

Continuing Learning
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<!doctype html><html> <head> <meta charset="UTF-8"> <title></title> <link rel="stylesheet" href="mycss.css" type="text/css"> </head> <body> <p><strong>我是黑色，因為我不在列表當中，所以這個規(guī)則對我不起作用</strong></p> <u1> <li><strong>我是紅色，這是因為 strong 元素位于 li 元素內(nèi)。</strong></li> </u1> </body> </html>
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