SOURCE

<ul class="clearfix">
  <li><a href="#div1">div1</a></li>
  <li><a href="#div2">div2</a></li>
  <li><a href="#div3">div3</a></li>
</ul>
<div class="box">
  <div class="div1" id="div1"></div>
  <div class="div2" id="div2"></div>
  <div class="div3" id="div3"></div>
</div>
  

ul{margin:0;padding:0}
li{list-style:none;float:left;display:block;padding:4px;}
.box,.div1,.div2,.div3{width:150px;height:100px;}
.box{overflow:hidden;}
.div1{background:red;}
.div2{background:green;}
.div3{background:blue;}
.clearfix:after { 
     visibility: hidden;
     display: block;
     font-size: 0;
     content: " ";
     clear: both;
     height: 0;
     }
.clearfix { display: inline-block; }
* html .clearfix { height: 1%; }
.clearfix { display: block; }