.banner1 {
    width:1100px;
    height:620px;
    margin:0 auto;
    position:relative;
    top:0px;
    left:0px;
}
.bannerimg {
    width:1100px;
    height:620px;
    position:absolute;
    top:0px;
    left:0px;
}
#banimg1 {
    background-image:url("../image/banner1-1.jpg");
}
#banimg2 {
    background-image:url("../image/banner1-2.jpg");
}
.banner1prev {
    width:200px;
    height:620px;
    position:absolute;
    top:0px;
    left:0px;
    background-color:black;
    opacity:0;
    filter:alpha(opacity=0);
}
    .banner1prev:hover {
        *filter: alpha(opacity=30);
    }
.banner1next {
    width: 200px;
    height: 620px;
    position: absolute;
    top: 0px;
    left: 900px;
    background-color: black;
    opacity: 0;
    filter: alpha(opacity=0);
}

    .banner1next:hover {
        *filter: alpha(opacity=50);
    }