.portfolioThumbs {float:left; margin-top:50px;}
.portfolioImg{border: 1px solid #ccc;}
.portfolioImg:hover{border: 1px solid navy;}
.portfolioImg:hover{
    color: red; /* irrelevant definition to overcome IE bug */
}
.portfolioImg{
    filter:alpha(opacity=50);
    -moz-opacity: 0.5;
    opacity: 0.5;
}
.portfolioImg:hover{
    filter:alpha(opacity=100);
    -moz-opacity: 1.0;
    opacity: 1.0;
}
a.prev img:hover {
    background: url(../images/diamondUp_on.png) no-repeat;
}

a.next img:hover {
    background: url(../images/diamondDown_on.png) no-repeat;
}