div#container{width:960px;margin:0 auto}
div#content{float:right;width:780px}
div#navigation{float:left;width:180px}
div#extra{float:left;clear:left;width:180px}
div#footer{clear:both;width:100%}
@media (max-width:960px){div#wrapper{margin-left:0}
div#content{float:none}
div#navigation{float:left;width:50%}
div#extra{float:left;width:50%;clear:none}}