<ul id="bubb">
  <li>
    Primo elemento
    <div>
      Tooltip del primo elemento
    </div>
  </li>
  <li>
    Secondo elemento
    <div>
      Tooltip del secondo elemento
    </div>
  </li>
  <li>
    Terzo elemento
    <div>
      Tooltip del terzo elemento
    </div>
  </li>
</ul>

* {
  font-size: 1.05em;
  font-family: 'Tahoma', arial;
}

#bubb li {
  cursor: pointer;
	display: inline-block;
	margin-left: 10px;
}

#bubb li > div {
  background: white;
  display: inline-block;
  font-size: 0.8em;
  margin-left: -135px;
  margin-top: 105px;
  min-height: 100px;
  padding: 15px;
  position: absolute;
  opacity: 0;
  visibility: hidden;
  width: 130px;

   /* border-radius */
  border-radius: 15px; /* W3C */
 
   /* box-shadow */
  -moz-box-shadow: 0 0 10px gray; /* Firefox */
  -webkit-box-shadow: 0 0 10px gray; /* Safari e Chrome */
  filter: progid:DXImageTransform.Microsoft.Shadow(color='#272229', Direction=135, Strength=3); /* IE */
  box-shadow: 0 0 10px gray; /* W3C */
 
 /* Transizione */
 -moz-transition: all 0.4s ease-in-out; /* Firefox */
  -webkit-transition: all 0.4s ease-in-out; /* Safari e Chrome */
  -o-transition: all 0.4s ease-in-out; /* Opera */
  transition: all 0.4s ease-in-out; /* W3C */
}

#bubb li:hover > div {
  margin-top: 40px;
  opacity: 1;
  visibility: visible;
  /* Transizione */
  -moz-transition: all 0.4s ease-in-out; /* Firefox */
  -webkit-transition: all 0.4s ease-in-out; /* Safari e Chrome */
  -o-transition: all 0.4s ease-in-out;  /* Opera */
  transition: all 0.4s ease-in-out; /* W3C */
}