Imitating calc() Fallback or Fixed-Width Sidebar In Responsive Layout Source:http://osvaldas.info/imitating-calc-fallback-fixed-width-sidebar-in-responsive-layout

calc.css

.content
{
    width: 80%; /* 960 */
    width: -webkit-calc( 100% - 15em ); /* 240 */
    width: -moz-calc( 100% - 15em ); /* 240 */
    width: calc( 100% - 15em ); /* 240 */
    float: left;
}
.sidebar
{
    width: 16.666%; /* 200 */
    width: -webkit-calc( 12.5em ); /* 200 */
    width: -moz-calc( 12.5em ); /* 200 */
    width: calc( 12.5em ); /* 200 */
    float: right;
}