#zt .prevBtn {
    width: 40px;
    height: 40px;
    background: url(ad_ctr.png) no-repeat 0 0;
	position: absolute;
    top: 30px;
    z-index: 10;
    cursor: pointer;
    text-indent: -9999px;
    filter: alpha(opacity=20);
    opacity: 0.2;
	display:none;
}
#zt .nextBtn {
    width: 40px;
    height: 40px;

    background: url(ad_ctr.png) no-repeat 0 0;
    background-position:0 -40px;
	position: absolute;
    top: 30px;
    z-index: 10;
    cursor: pointer;
    text-indent: -9999px;
    filter: alpha(opacity=20);
    opacity: 0.2;
	display:none;
}

.prevBtn {
    left: 16px;
}
.nextBtn {
    background-position: 0 -40px;
    right: 16px;
}
.prevBtn:hover,.nextBtn:hover { filter:alpha(opacity=50) !important;opacity:0.5 !important;  }