The Box Model - The CSS - page 76

Example 1:
div {
margin: 0;
padding: 50px;
border: 1px solid #999;
background: #ccc;
}
div div {
margin: 50px;
padding: 50px;
border: none;
background: #fff;
}
Example 2:
div {
margin: 0;
padding: 100px ;
border: 1px solid #999;
background: #ccc;
}
div div {
margin: 0;
padding: 0;
border: 50px solid #fff;
background: #fff;
}