.clear{clear:both;}
#wrapper{width:800px;}
#header{width:100%;height:100px;background:red;}
.inner_wrapper{width:100%;}
#left_side_bar{width:100px;height:400px;background:pink;}
#first{width:100px;height:10px;background:yellow;}
#second{width:100px;height:400px;background:gray;}
#third{width:50px;height:400px;background:brown;}
#fourth{width:50px;height:400px;background:purple;}
#footer{width:100%;height:100px;background:blue;}