How padding and border affect the expansion of elements in CSS
If a block has both padding and a border, they will both expand the block:
<div id="elem1"></div>
<div id="elem2"></div>
#elem1 {
width: 100px;
height: 100px;
background: #f1f1f1;
margin-bottom: 20px;
}
#elem2 {
width: 100px;
height: 100px;
background: #f1f1f1;
padding: 25px; /* set indents */
border: 10px solid green; /* set the boundary */
}
: