[css layout][18]Liquid, secondary columns fixed-width

1. left, left,left

   #wrapper {
     margin-left: 400px;
     float: left;
   }
   #navigation {
     width: 200px;
     float: left;
     margin-left: -100%;
   }
   #extra {
     width: 200px;
     float: left;
     margin-left: -100%;
     position: relative;
     left: 200px;
   }
   #footer {
     clear: both;
   }

2. right, right, right

   #wrapper {
     margin-left: 400px;
     float: right;
   }
   #navigation {
     width: 200px;
     float: right;
     margin-right: -200px;
   }
   #extra {
     width: 200px;
     float: right;
     margin-right: -400px;
   }
   #footer {
     clear: both;
   }