Div's in CSS gleich groß machen?

[Lupinus]

Ich probiere gerade ein Windows Design zu erstellen, scheitere jedoch an den Rändern ( http://eric.wiltfang.net/windoofs/test1.html ). Wie kann ich dafür sorgen, dass sie genau so hoch sind wie der Inhalt?

Hier der bisherige CSS-Code:

div.top_left{ height:30px; background-image:url(windoofs_top_left.png); width:33px;  margin:0px; padding:0px; float:left;}  
div.top_middle{ height:30px; background-image:url(windoofs_top.png); margin:0px; padding:0px; float:left;}  
div.top_right{ height:30px; background-image:url(windoofs_top_right.png); width:75px; margin:0px; padding:0px; float:left;}  
  
div.left{ background-image:url(windoofs_left.png); width:4px;  margin: 0 auto;; padding:0px; float:left; clear:both; cursor:w-resize;}  
div.content{ background-color:#ECE9D8; margin:0px; padding:5px; float:left;}  
div.right{ background-image:url(windoofs_right.png); width:4px; margin:0px; padding:0px; float:left; cursor:w-resize;}