Edit in JSFiddle

<div class="content-box">
  <p>content-box</p>
</div>

<div class="border-box">
  <p>border-box</p>
</div>

.content-box { 
  box-sizing: content-box; 
}
.border-box { 
  box-sizing: border-box; 
}

div{
  width: 300px;
  padding: 20px;
  background: #444;
  color: white;
  border: 10px solid black;
  background-clip: content-box;
  text-indent: 20px;
  
  margin:20px;
}