<style type="text/css">
.ToolText {
    position: relative;
    text-shadow: 0px 0px 3px #000;
}
.ToolTextHover {
    position: relative;
    text-shadow: 0px 0px 3px #000;
}
.ToolText span {
    display: none;
}

.ToolTextHover span {
  display: block;
  position: absolute;
  border: 1px solid black;
  top: 1.3em;
  left: 5px;
  background-color: gray;
  color: white;
  text-align: center;
}
</style>
<p class="ToolText" onMouseOver="javascript:this.className='ToolTextHover'" onMouseOut="javascript:this.className='ToolText'">SZÖVEG<span>TOOLTIP SZÖVEGE</span></p>