ME bug opacity

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=70); /* internet explorer */
	  -khtml-opacity: 0.7;      /* khtml, old safari */
  	-moz-opacity: 0.7;       /* mozilla, netscape */
  	opacity: 0.7;           /* fx, safari, opera */
}

.circCategoria .overlayTexto{
    position: absolute;
 
    filter: alpha(opacity=100); /* internet explorer */
	  -khtml-opacity: 1;      /* khtml, old safari */
	  -moz-opacity: 1;       /* mozilla, netscape */
	  opacity: 1;           /* fx, safari, opera */
    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;
}

.circCategoria .overlayTexto i{
    font-size: 40px;
}