DIVs Side by Side

Floats from left

HTML

<div class="left">left</div>
<div class="right">right</div>

CSS

.left{
  float:left;
  width:200px;
  background:red;
}
.right{
  height:100%;
  width:200px;

  background:green;
}

html, body{
    height:100%;
}