Expanding div vertically to accommodate content

[alenphp]

I have basically 3 divs. Top horizontal for title etc. And two vertical ones. Float left and float right. On the left side I input data in the form and it is shown on the right side. But when there is more posts div doesn't grow to accommodate all posts? 

header{
  	position:fixed;
  	top:0px;
  	height:15%;
  	left:0px;
  	right:0px;
  	background-color:#333;
  	color:#FFF;
  	z-index:10;
 	opacity:0.6;
 }
 #left{
 	position:absolute;
 	top:15%;
 	bottom:0px;
 	width:50%;
 	height:100%;
 	left:0px;
 	background-color:#900;
 	color:#FFF;
 	z-index:8;
 	overflow:hidden;
 	clear:both;
 }
 #right{
 	position:absolute;
 	top:15%;
 	bottom:0px;
 	width:50%;
 	height:100%;
 	right:0px;
 	background-color:#999;
 	color:#FFF;
 	z-index:8;
 	overflow:hidden;
 	clear:both;
 }

[BuildMyWeb]

it would help to see the file.  you are setting height in your columns and not sure what the containing element is.  for instance, if the containing element has a fixed height, and your columns are each set at

height:100%;

, i dont believe they will adjust vertically for more content.  and that content will be cutoff with

overflow:hidden;