Default Box Model

Code:
div {
	padding: 10px;
	border: 10px solid #eaeaea;
}

Border-box

Code:
div {
	padding: 10px;
	border: 10px solid #eaeaea;
	box-sizing: border-box;
	-moz-box-sizing: border-box; /*Firefox 1-3*/
	-webkit-box-sizing: border-box; /* Safari */
}