Template:Tooltip/styles.css

/* Tooltip container */
.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px black;
}

/* Tooltip text */
.tooltip .tooltiptext {
  visibility: hidden;
  width: 120px;
  background-color: black;
  color: #fff;
  text-align: center;
  padding: 5px 0;
  border-radius: 6px;
 
  /* Position the tooltip text - see examples below! */
  position: absolute;
  z-index: 1;
}

/* Show the tooltip text when you mouse over the tooltip container */
.tooltip:hover .tooltiptext {
  visibility: visible;
}