<div class="measure">220px</div>
<div class="box border-box">box-sizing: border-box;</div>
<div class="box">box-sizing: content-box;</div>
<div class="measure_bottom">280px</div>
.measure {
  text-align: center;
  margin-bottom: 10px;
  width: 220px;
  border-bottom: 1px dotted black;
}

.box {
  margin-bottom: 10px;
  border: 10px solid black;
  padding: 20px;
  width: 220px;
  height: 50px;
  background-color: white;
}

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

.measure_bottom {
  text-align: center;
  margin-bottom: 10px;
  width: 280px;
  border-bottom: 1px dotted black;
}

.box {
  font-size: 14px;
}
Rerun