<style>
.container {
  width: 500px;
  background-color: red;
}

.floated {
  float: left;
  background-color: transparent;
  width: 100px;
  height: 100px;
}

.clear-after {
  clear: both;
}

</style>
<div class=container><div></div><div class="floated"></div><span class=clear-after></span></div>