.cont_top {
 float: left;
 width: 590px; 
}
.cont_mid {
}
.cont_mid.left {
 float: left;
 text-align: left;
 width: 280px;
}
.cont_mid.right {
 float: right;
 text-align: left;
 width: 280px;
 margin-right: -12px;
}
.cont_bot {
 float: left;
 width: 590px; 
}