<div class="div1"></div>
<div class="div1"></div>
<div class="div1"></div>
<div style="clear:both;"></div>
<div class="div2">
  <span>HELLO</span>
  <div class="div3"></div>
</div>
.div1{
  float:left;
  width:100px;
  height:50px;
  background-color:red;
}

.div2{
  width:200px;
  height:200px;
  text-align:center;
  background-color:green;
}
.div3{
  width:150px;
  height:150px;
  background-color:blue;
  margin: 0 auto
}

External CSS

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External JavaScript

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