style.css

a.explain {
  border-bottom: 1px dotted __border__;
  padding-top: 0;
}

a.explain:hover {
  background-color: __light__;
  color: #000;
  position: relative;
}

div.dokuwiki a.explain span.tooltip {
  display: none;
  background-color: __background_neu__;
  color: __text_neu__;
  font-family: Verdana, 'Trebuchet MS', times;
  border:1px solid __border__;
  font-size:80%;
  line-height:1.2em;
  padding:4px 4px 8px 8px;
  text-align:left;
  position: relative;
}

/* IE/Win requires this */
div.dokuwiki a.explain:hover {font-size: 100%;}

/*the span will display just on :hover state*/
div.dokuwiki a.explain:hover span.tooltip {
  display: block !important;
  position: absolute;
  top: 5px;
  left: 40px;
  width: 150px;
  z-index:99 !important;
}