.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: none;
}

.tooltip .tooltiptext {
  visibility: hidden;
  width: 400px;
  background-color: blue;
  color: #fff;
  text-align: center;
  border-radius: 6px;
  padding: 5px 0;
  position: absolute;
  z-index: 1;
  bottom: 50%;
  right: 100%;
  margin-left: -60px;
  
  /* Fade in tooltip - takes 1 second to go from 0% to 100% opac: */
  opacity: 0;
  transition: opacity 1s;
}

.tooltip:hover .tooltiptext {
  visibility: visible;
  opacity: 1;
}