* {
  box-sizing: border-box;
}

 .tab { margin-left: 40px; }
 
/* Create three equal columns that floats next to each other */
.column50 {
  float: left;
  width: 46%;
  padding: 10px;
<!--
  height: 300px; /* Should be removed. Only for demonstration */
-->
}


/* Clear floats after the columns */
.row:after {
  content: "";
  display: table;
  clear: both;
}