<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<link rel="stylesheet" href="aa.css">
<style>
.c1{
background-color:pink;
height: 100px;
100px;
}
</style>
<link rel="stylesheet" href="bb.css">
</head>
<body>
<!--从标签为基准 由下到上依次查找-->
<div class="c1" style="background-color: green; height: 100px ; 100px;"></div>
</body>
</html>