.md-tooltip {
  display: none;
  position: absolute;
  z-index: 9999;
  line-height: 1.5;
  padding: 7px 10px;
  -webkit-border-radius: 4px;
          border-radius: 4px;
  background: #333;
  background: rgba(0, 0, 0, .8);
  color: #fff;
  font-size: 12px;
}
.md-tooltip:after {
  content: " ";
  position:absolute;
  left: 15px;
  top: -20px;
  width: 0;
  height: 0;
  margin: 0 0 0 -5px;
  border-top: 10px solid transparent;
  border-right: 5px solid  transparent;
  border-left: 5px solid transparent;
  border-bottom: 10px solid #333;
  border-bottom-color: rgba(0, 0, 0, .8);
}