Template:Tooltip/tooltip.css

.tooltip {
  position: relative;
  display: inline-block;
  cursor: help;
  text-decoration: underline dotted; /* underline dotted like <abbr> */
}

.tooltip .tooltiptext {
  visibility: hidden;
  background-color: #000; /* pure black */
  color: #fff;
  text-align: center;
  border-radius: 6px;
  padding: 6px;
  position: absolute;
  z-index: 1;
  bottom: 125%;
  left: 50%;
  transform: translateX(-50%);
  opacity: 0;
  transition: opacity 0.3s;
  white-space: normal; /* allow wrapping */
  max-width: 300px;    /* optional: limit width */
}

/* Tooltip arrow */
.tooltip .tooltiptext::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 50%;
  margin-left: -5px;
  border-width: 5px;
  border-style: solid;
  border-color: #000 transparent transparent transparent;
}

/* Show tooltip on hover */
.tooltip:hover .tooltiptext {
  visibility: visible;
  opacity: 1;
}