analytics/assets/css/tooltip.css

[tooltip]{
  position:relative;
  display:inline-block;
}

[tooltip]::before {
  transition: .3s;
  content: "";
  position: absolute;
  top:-6px;
  left:50%;
  transform: translateX(-50%);
  border-width: 4px 6px 0 6px;
  border-style: solid;
  border-color: rgba(0,0,0,0.8) transparent transparent transparent;
  z-index: 99;
  opacity:0;
}

[tooltip]::after {
  transition: .3s;
  white-space: nowrap;
  content: attr(tooltip);
  position: absolute;
  left:50%;
  top:-6px;
  transform: translateX(-50%)   translateY(-100%);
  background: rgba(0,0,0,0.8);
  text-align: center;
  color: #fff;
  font-size: .875rem;
  min-width: 80px;
  max-width: 420px;
  border-radius: 3px;
  pointer-events: none;
  padding: 4px 8px;
  z-index:99;
  opacity:0;
}

[tooltip]:hover::after,[tooltip]:hover::before {
   opacity:1
}