body {
    font-family: Arial, Helvetica, sans-serif;
    max-width: 500px;
    margin:auto;
    border:1px;
    padding:0 15px 0 15px;
}

.container-vertical {
  display:flex;
  flex-wrap: wrap;
  align-items: center;
}

.column{
  float: left;
  width: 50%;
}

.monocolumn {
  float: left;
  width: 100%;
}