.banner {
    width: 100%;
    height: 510px;
    background-color: white;
    position: relative;
    overflow: hidden;
    cursor: pointer;
}
.imgbox {
    width: 100%;
    height: 510px;
    position: relative;
    background-color: #222222;
    overflow: hidden;
}
.img {
    position: absolute;
    display: none;
    left: 0%;
    margin-left: 0px;
}
.im {
    display: block;
}
.change {
    height: 50px;
    display: block;
    position: absolute;
    z-index: 20;
    opacity: 0.4;
    transition: 0.4s;
    top: 50%;
    margin-top: -50px
    visibility:no
}
.change:hover {
    opacity: 0.5;
}
.pre {
    left: 1%;
}
.next {
    right: 1%;
}
.cirbox {
    width: 88px;
    position: absolute;
    bottom: 15px;
    z-index: 10;
    left: 50%;
    margin-left: -44px;
    cursor: pointer;
}
.cir {
    width: 12px;
    height: 12px;
    background-color: white;
    opacity: 0.4;
    float: left;
    border-radius: 6px;
    margin: 0 5px 0 5px;
    cursor: pointer;
}
.cir:hover {
    background-color: white;
    transition: 0.8s;
}
.cr {
    opacity: 1;
}
.cr:hover {
    background-color: white;
}