<div class="left">左</div> <div class="right">右</div> <div class="center">中</div>
html,body{margin:0; padding: 0;}
.left,.right,.center { height: 200px; line-height:200px; text-align:center; }
.left {float:left; width: 200px; background-color: #ccc;}
.right {float:right; width: 200px; background-color: #ccc;}
.center { margin: 0 210px; background-color: #666;}