<h1>Default Box-Sizing</h1>
<div class="box_one">
  Content Box 1
</div>

<h1>Box-Sizing with Border-Box Value</h1>
<div class="box_two">
  Content Box 2
</div>

.box_one {
  padding: 10px;
  width: 200px;
  height: 150px;
  border: 10px solid seagreen;
  background: lemonchiffon;
}

.box_two {
  padding: 10px;
  width: 200px;
  height: 150px;
  border: 10px solid seagreen;
  background: lemonchiffon;
  box-sizing: border-box;
}