ME bug opacity

by rapa09

HTML

<a href="#" class="circCategoria">
  <img src="http://i382.photobucket.com/albums/oo262/Don_M85/mazda-rx8-rc-car.jpg" alt="" />
  <div class="overlay">
    <span class="overlayTexto">
            more</span>
    <span class="overlayFundo"></span>
  </div>
</a>

CSS

.circCategoria {
  position: relative;
  z-index: 10;
  border: solid 8px #00601b;
  overflow: hidden;
  width: 250px;
  height: 250px;
  border-radius: 50%;
  display: block;
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

.circCategoria img {
  padding: 10px;
  background: white;
}

.circCategoria .overlay {
  filter: alpha(opacity=0);
  /* internet explorer */
  -khtml-opacity: 0;
  /* khtml, old safari */
  -moz-opacity: 0;
  /* mozilla, netscape */
  opacity: 0;
  /* fx, safari, opera */
  -webkit-transition: all 0.5s, background 0.5s;
  transition: all 0.5s, background 0.5s;
}

.circCategoria:hover .overlay {
  filter: alpha(opacity=100);
  /* internet explorer */
  -khtml-opacity: 1;
  /* khtml, old safari */
  -moz-opacity: 1;
  /* mozilla, netscape */
  opacity: 1;
  /* fx, safari, opera */
  -webkit-transition: all 0.5s, background 0.5s;
  transition: all 0.5s, background 0.5s;
}

.circCategoria .overlay .overlayFundo {
  position: absolute;
  top: 0px;
  width: 100%;
  height: 100%;
  left: 0px;
  background: #eee808;
  z-index: 5;
  filter: alpha(opacity=0);
  /* internet explorer */
  -khtml-opacity: 0;
  /* khtml, old safari */
  -moz-opacity: 0;
  /* mozilla, netscape */
  opacity: 0;
  /* fx, safari, opera */
  transition: all 0.5s, background 0.5s;
}

.circCategoria .overlayTexto {
  position: absolute;
  transition: all 0.5s, background 0.5s;
  font-size: 21px;
  font-weight: bold;
  line-height: 22px;
  color: #01611b;
  width: 100%;
  top: 50%;
  margin-top: -30px;
  left: 0px;
  text-align: center;
  z-index: 6;
  filter: alpha(opacity=0);
  /* internet explorer */
  -khtml-opacity: 0;
  /* khtml, old safari */
  -moz-opacity: 0;
  /* mozilla, netscape */
  opacity: 0;
  /* fx, safari, opera */
}

.circCategoria:hover .overlayTexto, .circCategoria .overlay:hover .overlayFundo {
  filter: alpha(opacity=70);
  /* internet explorer */
  -khtml-opacity: 0.7;
  /* khtml, old safari */
  -moz-opacity:...