Chapter 4 Box model

1. box 无处不在

2. box 的并列关系和嵌套关系

preview

Source code

<!-- html -->
<div>
    content
</div>

div {
    background: #ddd;
    border: 20px solid #cfc;
    height: 50px;
    margin: 50px;
    pading: 30px;
}