Aide Avec colonnes Css - passant de 3 à 2?

* {
   margin: 0px;
   padding: 0px;
}
body {
   background-image: url(../images/Page_Back.png);
   background-color: #ca6223;
   background-repeat: repeat-x;
   text-align: center;
}
.maintxt {
   font-family: Verdana, Arial, Helvetica, sans-serif;
   font-size: 11px;
   font-style: normal;
   line-height: 15px;
   color: #000000;
}
.maintxt_bold {
   font-family: Verdana, Arial, Helvetica, sans-serif;
   font-size: 11px;
   font-style: normal;
   line-height: 15px;
   color: #000000;
   font-weight: bold;
}
.maintxt_bold2 {
   font-family: Verdana, Arial, Helvetica, sans-serif;
   font-size: 13px;
   font-style: normal;
   line-height: 15px;
   color: #000000;
   font-weight: bold;
}
.maintxt_italic {
   font-family: Verdana, Arial, Helvetica, sans-serif;
   font-size: 11px;
   font-style: italic;
   line-height: 15px;
   color: #000000;
}
a img {
   border-top-style: none;
   border-right-style: none;
   border-bottom-style: none;
   border-left-style: none;
}
#wrapper {
   background-color: #FFF;
   width: 794px;
   margin-right: auto;
   margin-left: auto;
   text-align: left;
   border-style: solid;
   border-color: #1b1040;
   border-width: 1px;
}
#wrapper #white_top {
   background-color: #FFF;
   height: 15px;
}
#wrapper #logo {
   background-color: #FFF;
}
#wrapper #header {
   background-position: center center;
   background-image: url(../images/Banner.png);
   background-repeat: no-repeat;
   background-color: #FFF;
   text-align: center;
   vertical-align: baseline;
   margin: 0px;
   padding: 0px;
}
#wrapper #menu {
   background-image: url(../images/Menu_Bar_Back.jpg);
   background-repeat: no-repeat;
   margin-right: auto;
   margin-left: auto;
   height: 35px;
   width: 790px;
   padding: 0px;
}
#container {
width: 98%;
margin: 5px auto;
background-color: #fff;
color: #333;
border: 1px solid gray;
line-height: 130%;
}
#leftnav {
float: left;
width: 130px;
margin: 0;
margin-top: 0px;
padding-right: 15px;
padding-left: 0px;
}
#rightnav {
float: right;
width: 140px;
margin: 0;
margin-top: 5px;
padding-right: 15px;
padding-left: 0px;
}
#content {
margin-left: 160px;
border-left: 1px solid gray;
margin-right: 160px;
border-right: 1px solid gray;
padding: 1em;
}
#wrapper #main #footer {
   height: 16px;
   clear: both;
   margin: 0px;
   padding: 0px;
}
#wrapper #main #bottom1 {
   height: 30px;
   margin: 0px;
   padding: 0px;
}
#bottom2 {
   background-color: #ca6223;
   height: 20px;
}
.indentmenu{
   width: 100%; /*leave this value as is in most cases*/
   overflow: hidden;
   margin-right: auto;
   margin-left: auto;
   font-family: Arial;
   font-size: 12px;
   text-align: center;
   }
 
.indentmenu ul{
   margin: 0;
   float: right;
   width: 100%; /*width of menu*/
   padding-top: 7px;
   padding-right: 0;
   padding-bottom: 0;
   padding-left: 0;
}
 
.indentmenu ul li{
display: inline;
}
 
.indentmenu ul li a{
   float: inherit;
   color: #8781bd; /*text color*/
   padding: 1px 12px;
   text-decoration: none;
   
}
.indentmenu ul li a:hover, .indentmenu ul li .current{
color: white; !important; /*text color of selected and active item*/
padding-top: 6px; /*shift text down 1px for selected and active item*/
padding-bottom: 4px; /*shift text down 1px for selected and active item*/
}
 
.menu_spacing {
   font-family: Arial;
   font-size: 12px;
   text-align: center;
   line-height: normal;
   margin-left: 20px;
   margin-right: 20px;
}
.news_back_old {
   background-image: url(../images/News_2.png);
   width: 152px;
   height: 122px;
   background-repeat: no-repeat;
}
.news_back {
   background-image: url(../images/Newsletter.png);
   width: 148px;
   height: 276px;
   background-repeat: no-repeat;
}
img.floatLeft {
    float: left;
    margin: 4px;
}