<div class="parent">
  <div style="clear: both;"></div>
  <div class="child">
    child element
  </div>
</div>

.parent,
.child {
  margin: 12px auto;
}

.parent {
  background: peachpuff;
  padding: 0 12px;
}

.child {
  background: lightblue;
}

.parent:after {
  content: "after parent element";
}