<!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>
/* (3,0,0)，注意继承的选择器，权重可以看做是0，权重绝对没有选中的大 */
#box1 #box2 #box3 {
color: red;
}
/* (0,0,1) */
p {
color: green;
}
</style>
</head>
<body>
<div id="box1" class="box1">
<div id="box2" class="box2">
<div id="box3" class="box3">
<p>我是文字</p>
</div>
</div>
</div>
</body>
</html>