I think you don't really need those additional columns. Just combine both gradients into one and assign it to the main column:
.container_body {
background: #fff;
background: -moz-linear-gradient(left, #c6c6c6 0%, #ffffff 2%, #ffffff 98%, #c6c6c6 100%);
background: -webkit-gradient(linear, left top, right top, color-stop(0%,#c6c6c6), color-stop(2%,#ffffff), color-stop(98%,#ffffff), color-stop(100%,#c6c6c6));
background: -webkit-linear-gradient(left, #c6c6c6 0%,#ffffff 2%,#ffffff 98%,#c6c6c6 100%);
background: -o-linear-gradient(left, #c6c6c6 0%,#ffffff 2%,#ffffff 98%,#c6c6c6 100%);
background: -ms-linear-gradient(left, #c6c6c6 0%,#ffffff 2%,#ffffff 98%,#c6c6c6 100%);
background: linear-gradient(to right, #c6c6c6 0%,#ffffff 2%,#ffffff 98%,#c6c6c6 100%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#c6c6c6', endColorstr='#c6c6c6',GradientType=1 );
}