SOURCE

<div class="container">
  <span class="test1"></span>
  <span class="test2"></span>
</div>

.container {
  width: 200px;
  display: inline-flex;
  flex-direction: column;
  line-height: 2;
}
.test1 {
  background: red;
  width: 100%;
}
.test2 {
  background: red;
  width: 100%;
}
.test2::after {
  content: '';
  display: inline-block;
}