0. 使用 box-sizing: border-box
1. html page:<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<link rel="stylesheet" href="The_box_model.css" >
<title>Title</title>
</head>
<body>
<div class="box"></div>
</body>
</html>
2. css
html {
box-sizing: border-box;
}
*, *::before, *::after {
box-sizing: inherit;
}
.box {
350px;
height: 150px;
margin: 10px;
padding: 25px;
border: 5px solid black;
}