SOURCE

<div class="container">
  <div class="middle">中间</div>
  <div class="left">左边</div>
  <div class="right">右边</div>
</div>

.container{
  height:200px;
  padding:0 200px;
}
.middle{
  width:100%;
  height:200px;
  background-color:red;
  float:left;
}
.left{
  height:200px;
  width:200px;
  background-color:yellow;
  float:left;
  margin-left:-100%;
}
.right{
  width:200px;
  height:200px;
  background-color:black;
  float:left;
  color:red;
  margin-left:-200px;
}