#leftnav
{
float: left;
width: 210px;
margin: 0;
padding: 1em;
}

#rightnav
{
float: right;
width: 210px;
margin: 0;
padding: 1em;
}

#content
{
margin-left: 240px;
border-left: 1px solid gray;
margin-right: 240px;
border-right: 1px solid gray;
padding: 1em;
max-width: 36em;
}