*, *:before, *:after {
  -moz-box-sizing: border-box; -webkit-box-sizing: border-box; box-sizing: border-box;
}
 
body { margin: .5em; }
 
.columnsContainer { position: relative; margin: 0em; }
 
.leftColumn {  margin-bottom: .5em; top: 0; }
 
.rightColumn { margin-bottom: .5em; top: 0; }

@media screen and (min-width: 47.5em ) {
  .rightColumn { position:absolute; top:0; right:0; width: 49.5%;   }
 
  .leftColumn { position:absolute; top:0; left:0; width:49.5%;  }
}