.page-wrap {

  display: -webkit-box;      /* OLD - iOS 6-, Safari 3.1-6 */

  display: -moz-box;         /* OLD - Firefox 19- (buggy but mostly works) */

  display: -ms-flexbox;      /* TWEENER - IE 10 */

  display: -webkit-flex;     /* NEW - Chrome */

  display: flex;             /* NEW, Spec - Opera 12.1, Firefox 20+ */

 }    

.main-content {

  width: %;

}

.main-nav,

.main-sidebar {

  -webkit-box-flex: ;      /* OLD - iOS 6-, Safari 3.1-6 */

  -moz-box-flex: ;         /* OLD - Firefox 19- */

  width: %;               /* For old syntax, otherwise collapses. */

  -webkit-flex: ;          /* Chrome */

  -ms-flex: ;              /* IE 10 */

  flex: ;                  /* NEW, Spec - Opera 12.1, Firefox 20+ */

}