.tooltip{
      position: relative;
      display: inline-block;
      border-bottom: 1px dotted black;
  }
  .tooltip .tooltiptext {
      visibility: hidden;
      width: 120px;
      background-color: black;
      color: #fff;
      text-align: center;
      padding: 5px 0;
      border-radius: 6px;    
      position: absolute;
      z-index: 1;
  }
  .tooltip:hover .tooltiptext {
      visibility: visible;
  }
    }