tooltip.css

 /* Tooltip container */
 .tool {
    position: relative;
    display: inline-block;
    /*border-bottom: 1px dotted black; /* If you want dots under the hoverable text */
  }
  
  /* Tooltip text */
  .tool .tooltip {
    visibility: hidden;
    width: 120px;
    background-color: rgb(255, 255, 0);
    color: #000;
    text-align: center;
    padding: 2px 0;
    border-radius: 6px;
  
    /* Position the tooltip text */
    position: absolute;
    z-index: 1;
    bottom: 100%;
    left: 50%;
    margin-left: -60px;

    font-family: Arial, Helvetica, sans-serif;
    font-size: 12px;
  
    /* Fade in tooltip */
    opacity: 0;
    transition: opacity 0.3s;
  }
  
  /* Tooltip arrow */
  .tool .tooltip::after {
    content: "";
    position: absolute;
    top: 100%;
    left: 50%;
    margin-left: -5px;
    border-width: 5px;
    border-style: solid;
    border-color: rgb(255, 255, 0) transparent transparent transparent;
  }
  
  /* Show the tooltip text when you mouse over the tool */
  .tool:hover .tooltip {
    visibility: visible;
    opacity: 1;
  }