<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> /* 权重(2, 0, 1) */ #box1 #box2 p { color: red; } /* 权重(2, 1, 2) */ #box1 div.box2 #box3 p { color: green; } /* 权重(0, 3, 1) */ .box1 .box2 .box3 p { color: blue; } /* 权重(0, 1, 1) */ .list li { color: red; } /* 权重(0, 1, 0) */ .spec { color: blue !important; } </style> </head> <body> <div id="box1" class="box1"> <div id="box2" class="box2"> <div id="box3" class="box3"> <p>我是段落</p> </div> </div> </div> <ul class="list"> <li>列表项</li> <li class="spec">列表项</li> <li class="spec">列表项</li> <li>列表项</li> <li>列表项</li> <li>列表项</li> <li>列表项</li> </ul> </body> </html>
规定：id权重>类权重>标签权重
复杂选择器可以通过（id个数、class个数、标签个数）的形式计算权重
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> <style> /* 权重(2, 0, 1) */ #box1 #box2 p { color: red; } /* 权重(2, 1, 2) */ #box1 div.box2 #box3 p { color: green; } /* 权重(0, 3, 1) */ .box1 .box2 .box3 p { color: blue; } /* 权重(0, 1, 1) */ .list li { color: red; } /* 权重(0, 1, 0) */ .spec { color: blue !important; } </style> </head> <body> <div id="box1" class="box1"> <div id="box2" class="box2"> <div id="box3" class="box3"> <p>我是段落</p> </div> </div> </div> <ul class="list"> <li>列表项</li> <li class="spec">列表项</li> <li class="spec">列表项</li> <li>列表项</li> <li>列表项</li> <li>列表项</li> <li>列表项</li> </ul> </body> </html>
原文：https://www.cnblogs.com/xingcenxinyi/p/14864946.html