#framecontentBottom{
position: absolute;
top: auto; 
left: 200px; /*Set left value to WidthOfLeftFrameDiv*/
width: auto;
bottom: 0;
right: 0;
height: 90px; /*Height of bottom frame div*/
overflow: hidden; /*Disable scrollbars. Set to "scroll" to enable*/
background-color: #CCC;
}

#maincontent{
bottom: 90px;
}

* html body{ /*IE6 hack*/
padding: 0 0 90px 200px; /*Set value to (0 0 HeightOfTopFrameDiv WidthOfLeftFrameDiv)*/
}

* html #framecontentBottom{
width:100%;
}