<div class="parents">
  Parent Div
  <div class="children" >Child Div (100&times;100)</div>
</div>

<br />

<div class="parents">
  Parent Div
  <div class="children" style="float:left">Floating Child Div (100&times;100)</div>
</div>

.parents{
  background: yellow;
  font-family:cambria;
  
}

.children{
  width: 100px;
  height: 100px;
  background: pink;
}