.tt {
  display: none;
  position: absolute;
  color: #FFF;
  text-align: center;
  padding: 10px;
  max-width: 200px;
  background-color: #000;
  border-radius: 3px;
}

.tt.visible { display: inline-block; }

.tt:after {
  content: '\25be';
  color: black;
  font-size: 18px;
  position: absolute;
  height: 10px;
  bottom: 0;
  left: 50%;
  margin-left: -5px;
}

.center {
  margin: 150px auto;
  text-align: center;
}